A mirror brake mechanism of an SLR camera for applying a brake to a mirror pivoted about a mirror rotational shaft to be swingable between a viewing position and a retracted position. The mirror brake mechanism includes a brake shaft which is independent of the mirror rotational shaft and positionally aligned along an extension line of the mirror rotational shaft; an interlocking rotating member disposed on one of laterally opposite sides of the mirror and rotatable about the brake shaft; a mirror drive shaft which connects a mirror seat, on which the mirror is mounted, and the interlocking rotating member to each other in a rotational direction about the mirror drive shaft; a brake drum which rotates in association with the interlocking rotating member; and a mirror brake member which is brought into contact with and disengaged from the brake drum.