The present invention provides a highly operable easy-to-use camera having a simple configuration without losing a locking function. In a camera comprising: a rotary operation dial 7 to be operated rotationally; a lock arm 5 for locking the rotary operation dial 7 relative to a predetermined position; and a body case 2 to be fitted with the rotary operation dial 7 and the lock arm 5, a rotary operation portion 71 of the rotary operation dial 7 and a button operation portion 51 of the lock arm 5 are disposed in proximity to each other on adjacent faces of the body case 2; a lock groom 73 formed in a predetermined position of a lower face rib 72 of the rotary operation dial 7, the lower face rib 72 lying inside the body case 2, is arranged in such a manner that a fitting portion 53 of the lock arm 5 can be fitted thereinto; and an urging means 9 for urging the lock arm 5 from inside to outside of the body case 2 is provided.