An image sensor test system (10) bringing input/output terminals of an image sensor into contact with a contact (61) of a test head (60), emitting light to alight receiving surface of the image sensor from a light source (80) and, while doing so, inputting/outputting electrical signals between the contact (61) of the test head (60) and the image sensor so as to test the optical properties of the image sensor, provided with a loader use inverting device (32) for inverting an image sensor loaded into a supply tray stacker in a state with the light receiving surface facing upward, a contact arm (43) for gripping a back surface of an opposite side to the light receiving surface of the image sensor and moving the image sensor to bring the image sensor into contact with a contact (61) of the test head (60) in the state with the light receiving surface facing downward, and an unloader use inverting device inverting and unloaded the tested image sensor.