An angle adjustor includes a fixed member, a movable member, a plurality of friction plates arranged between the fixed and movable members, and a bolt connecting the fixed and movable members. The fixed member and the movable member each have a notch for receiving a pressing member that presses the friction plates against the surface of the notch. Each pressing member is fixed to the fixed member or movable member in a direction substantially parallel to the axis of the bolt. The friction plates are fixed between the notch and the pressing member.