To obtain a reciprocating mechanism with a simple and compact structure.

Two grooves 16, 16 are slantingly receessed on the outer periphery of the slide part 14 of a slider 12 whose rotation is regulated and steel balls 18, 18 in the through holes 17, 17 of a rotary sleeve 10 are in the grooves 16, 16 at the most rear position. Two second grooves 21, 21 are slantingly recessed on the outer periphery of the rotary sleeve 10, too and the steel balls 23, 23 in the through hole 22, 22 of the second slider 19 externally equiped to the rotary sleeve 10 are fitted in the second grooves 21, 21 at the most rear position.