PURPOSE: To reduce a high stress applied on an image sensor, a coupling part between the image sensor and a sensor board, and the sensor board by cantilevering the sensor board to which a sensor holder including the image sensor held thereon is fixed.

CONSTITUTION: An image sensor 2 and a sensor board 4 are soldered to each other with the use of a jig, and the image sensor 2 is fixed to a sensor holder 1 using a leaf spring 3, and further the sensor holder 1 and the sensor board are fixed to each other through a screw 5. Thereupon, once the image sensor 2 and the sensor holder 1 are completely fixed to each other. There is applied force W which pulls down the sensor board 4, through the soldered portion. A portion of the sensor board 4 where the sensor board 4 is fixed to the sensor holder 1 through the screw 5 is cantilevered, whereby a load to the image sensor 2 due to a load to the image sensor 2 due to deflection of the sensor board 4 is sharply reduced without depending on the pitch L2 of the screw 5.