PURPOSE: To reduce remarkably number of segments of an optical sensor in comparison with number of obtained electric signals by providing an optical shutter section comprising electrooptic elements having plural segments driven sequentially electrically into the photo transmitting state or the non-phototransmitting state.

CONSTITUTION: The image of a detected light from a body to be detected is formed by an objective lens 2 to an optical shutter section 1, the segments A1, A2, A3 and A4 of the optical shutter section 1 are brought sequentially into the photo transmitting state in the side order, and the detected light transmitting through the said segments A1, A2, A3 and A4 is received by an optical sensor section 3 so as to output an electric signal, then the provision of the optical sensor section 3 comprising one segment is enough to obtain four electric signals required for the image pickup of the object and then the variance of the light sensitivity of the optical sensor section 3 is no problem, and no mechanical drive means is required, deformation of the image is not problem, the sensor is manufactured inexpensively and only one output circuit to extract the electric signal from the optical sensor section 3 is needed, then the photo detection circuit being the signal processing circuit is constituted simply.