A thrust converting mechanism has a shaft provided with a pair of helical mated portions, formed in mutually opposing directions; a pair of linear motion members having mating portions for engaging, respectively, the pair of mated portions; a case for supporting the pair of linear motion members so as to enable movement along the shaft, and for bearing the shaft rotatably; a rocking member that is borne on one of the linear motion members of the pair, and for engaging with the other linear motion member of the pair, and for rocking through relative motion of the shaft in respect to the case; and a moving member, supported on the case, that engages with the rocking member to move, through rocking of the rocking member, in a direction that crosses the shaft.