To assure stable operation of a key top, with miniaturization being promoted.

An electronic apparatus includes a case in which predetermined parts are arranged, and an operation unit arranged in the case. The operation unit includes a key top containing at least three cam engagement parts, which are moved under pressing operation, to be spaced around the axis of movement direction, a rotary cam in which the cam engagement part contains at least three cam parts which are engaged together for sliding, to be spaced around the axis, and, when the key top is pressed, the cam engagement part and the cam part are slid to be rotated around the axis, and an energizing spring which energizes in the direction opposite to the moving direction when the key top is pressed.