To provide a spindle mechanism which ensures rocking return of a spindle.

According to the spindle mechanism, a spindle spring 18 is elastically mounted on a spring engageable shaft 17 which is protruded outside a partition plate 16 arranged at an innermost edge of an inner cylinder, and the spring bears the spindle 2 for supporting a lever tumbler so as to be rockably rotatable about an eccentric shaft 3 protruding on both edges thereof, followed by engaging the other end of the spindle spring 18 with the spindle 2 from below. Further the spindle spring 18 has a chevron-shaped portion 19 protruding in a spindle 2 direction, formed at the other end thereof, and when the spindle 2 is rotated in a manner pressing downward the other end of the spindle spring 18, the spindle 2 engages with an inclined portion of the chevron-shaped portion 19.