A lens barrel holding apparatus includes a first holding member, a second holding member attached to the first holding member in an openable/closable manner for fastening a lens barrel in cooperation with the first holding member to hold the lens barrel and a fastening mechanism for applying a force for fastening the lens barrel, to the second holding member. The fastening mechanism includes an engagement surface provided on the second holding member and a fastening member provided on the first holding member, adapted to move straightly toward/away from the engagement surface, and having a contact surface that can be in contact with the engagement surface. At least one of the contact surface and the engagement surface is slanted with respect to the movement direction of the fastening member.