Vision sensor including a voltage generation circuit for outputting a test bias voltage to a transistor and operating method thereof

A vision sensor and an operating method of the vision sensor are provided. The vision sensor includes a pixel array including a plurality of pixels arranged in a form of a matrix; and a bias voltage generation circuit configured to provide a test bias voltage to the pixel array, wherein each of the plurality of pixels includes a sensing circuit configured to sense light and generate a first output voltage, wherein the first output voltage changes as the test bias voltage changes within a specific frame.