One end of a cable connecting fitting is fixed to a transmission cable. After a locking claw provided on the other end of the cable connecting fitting is locked to the tip surface of a mounting tube portion of a prism holder, the mounting tube portion and the cable connecting fitting are fixed to each other. An image area sensor is close to the inner circumferential surface of a distal end hard portion, and a camera module is disposed in the distal end hard portion. The cable connecting fitting can be disposed at a free space between the inner circumferential surface of the distal end hard portion and the image area sensor. The size of the cable connecting fitting can be increased within a range of the free space, connection strength is secured, and separation of the prism or junctions and rupture of the transmission cable can be suppressed.