An operation apparatus inhibits separation of a holding member for holding an operation knob from a circuit board. A holding member holding a rotation operation knob so as to be rotatable includes a latched portion capable of insertion through a through-hole formed on a circuit board and also capable of flexure deformation in a specified line parallel to the circuit board. On a rear end of the latched portion, a latched projection is provided projecting to a first direction of the specified line. Accompanying flexure deformation of the latched portion in a second direction opposite to the first direction, the latched projection is able to pass through the through-hole by displacing a predetermined amount in the second direction. The rear cover includes a deformation regulator contacting the latched projection from the second direction and regulates displacement of the latched projection in the second direction to less than the pre-determined amount.