To provide a detent structure having improved productivity and reduced production cost while reducing the number of components to allow easy machining and assembling efficiency of the components.

In the detent structure 60, an attractive face 61 of an operation shaft 52 perpendicular to the center axis of the operation shaft 52 is opposed to an attractive face 71 of a rotation restricting member 70 in a magnetically attractive manner, the rotation restricting member 70 is engaged with a housing so as to be rotation-preventive and to be linearly movable with its attractive face 71 movable close to or apart from the attractive face 61 of the operation shaft 52, and a protrusion 73 is provided on one of the attractive face 61 of the operation shaft 52 and the attractive face 71 of the rotation restricting member 70 and a recessed groove 63 is provided in the other for completely storing the protrusion 73.

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