An optical mouse, with shade compensation, has a light source, a sensor and a controller. The light source illuminates a sampling plane of a mouse. The sensor consists of a 2-dimensional array of sensing elements to capture an image from the sampling plane and temporarily store the image into a 2-dimensional array of pixels, each having a pixel value. The controller is connected to the sensor for adjusting the pixel values according to a predetermined table, thereby achieving a shade compensation for the sensing elements.