In an accessory shoe member placed on top of a base member, a pair of engagement portions is formed in a first direction perpendicular to an attachment direction of an external accessory device, and a plurality of fastening holes is formed side by side in the first direction. A plurality of fastening members is inserted into the plurality of fastening holes with the accessory shoe member placed on top of the base member, thereby fastening the base member and the accessory shoe member to an imaging apparatus. In the accessory shoe member, a joining portion joining the pair of engagement portions is formed. The accessory shoe member is formed by bending a plate metal material into a loop shape so that a joint is located between the plurality of fastening holes.