diff --git a/src/main/java/cc/ryanc/halo/exception/AlreadyExistsException.java b/src/main/java/cc/ryanc/halo/exception/AlreadyExistsException.java
new file mode 100644
index 000000000..22aa88882
--- /dev/null
+++ b/src/main/java/cc/ryanc/halo/exception/AlreadyExistsException.java
@@ -0,0 +1,18 @@
+package cc.ryanc.halo.exception;
+
+/**
+ * Exception caused by entity existence already.
+ *
+ * @author johnniang
+ */
+public class AlreadyExistsException extends BadRequestException {
+
+    public AlreadyExistsException(String message) {
+        super(message);
+    }
+
+    public AlreadyExistsException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+}
diff --git a/src/main/java/cc/ryanc/halo/exception/BadRequestException.java b/src/main/java/cc/ryanc/halo/exception/BadRequestException.java
new file mode 100644
index 000000000..ed4ad883a
--- /dev/null
+++ b/src/main/java/cc/ryanc/halo/exception/BadRequestException.java
@@ -0,0 +1,24 @@
+package cc.ryanc.halo.exception;
+
+import org.springframework.http.HttpStatus;
+
+/**
+ * Exception caused by bad request.
+ *
+ * @author johnniang
+ */
+public class BadRequestException extends HaloException {
+
+    public BadRequestException(String message) {
+        super(message);
+    }
+
+    public BadRequestException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    @Override
+    public HttpStatus getStatus() {
+        return HttpStatus.BAD_REQUEST;
+    }
+}
diff --git a/src/main/java/cc/ryanc/halo/exception/ForbiddenException.java b/src/main/java/cc/ryanc/halo/exception/ForbiddenException.java
new file mode 100644
index 000000000..ee2a6d572
--- /dev/null
+++ b/src/main/java/cc/ryanc/halo/exception/ForbiddenException.java
@@ -0,0 +1,24 @@
+package cc.ryanc.halo.exception;
+
+import org.springframework.http.HttpStatus;
+
+/**
+ * Exception caused by accessing forbidden resources.
+ *
+ * @author johnniang
+ */
+public class ForbiddenException extends HaloException {
+
+    public ForbiddenException(String message) {
+        super(message);
+    }
+
+    public ForbiddenException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    @Override
+    public HttpStatus getStatus() {
+        return HttpStatus.FORBIDDEN;
+    }
+}
diff --git a/src/main/java/cc/ryanc/halo/exception/HaloException.java b/src/main/java/cc/ryanc/halo/exception/HaloException.java
new file mode 100644
index 000000000..199326174
--- /dev/null
+++ b/src/main/java/cc/ryanc/halo/exception/HaloException.java
@@ -0,0 +1,46 @@
+package cc.ryanc.halo.exception;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.lang.NonNull;
+import org.springframework.lang.Nullable;
+
+/**
+ * Base exception of the project.
+ *
+ * @author johnniang
+ */
+public abstract class HaloException extends RuntimeException {
+
+    /**
+     * Error errorData.
+     */
+    private Object errorData;
+
+    public HaloException(String message) {
+        super(message);
+    }
+
+    public HaloException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    @NonNull
+    public abstract HttpStatus getStatus();
+
+    @Nullable
+    public Object getErrorData() {
+        return errorData;
+    }
+
+    /**
+     * Sets error errorData.
+     *
+     * @param errorData error data
+     * @return current exception.
+     */
+    @NonNull
+    public HaloException setErrorData(@Nullable Object errorData) {
+        this.errorData = errorData;
+        return this;
+    }
+}
diff --git a/src/main/java/cc/ryanc/halo/exception/NotFoundException.java b/src/main/java/cc/ryanc/halo/exception/NotFoundException.java
new file mode 100644
index 000000000..08d965fe5
--- /dev/null
+++ b/src/main/java/cc/ryanc/halo/exception/NotFoundException.java
@@ -0,0 +1,24 @@
+package cc.ryanc.halo.exception;
+
+import org.springframework.http.HttpStatus;
+
+/**
+ * Exception of entity not found.
+ *
+ * @author johnniang
+ */
+public class NotFoundException extends HaloException {
+
+    public NotFoundException(String message) {
+        super(message);
+    }
+
+    public NotFoundException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    @Override
+    public HttpStatus getStatus() {
+        return HttpStatus.NOT_FOUND;
+    }
+}
diff --git a/src/main/java/cc/ryanc/halo/exception/ServiceException.java b/src/main/java/cc/ryanc/halo/exception/ServiceException.java
new file mode 100644
index 000000000..47e7d24b4
--- /dev/null
+++ b/src/main/java/cc/ryanc/halo/exception/ServiceException.java
@@ -0,0 +1,24 @@
+package cc.ryanc.halo.exception;
+
+import org.springframework.http.HttpStatus;
+
+/**
+ * Exception caused by service.
+ *
+ * @author johnniang
+ */
+public class ServiceException extends HaloException {
+
+    public ServiceException(String message) {
+        super(message);
+    }
+
+    public ServiceException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    @Override
+    public HttpStatus getStatus() {
+        return HttpStatus.INTERNAL_SERVER_ERROR;
+    }
+}