A syringe includes a gasket, a barrel, and a plunger. The plunger includes a helical rib provided on an outer surface of a head portion, and the gasket comprises a helical valley portion for threadedly engaging with the helical rib, a plunger-retaining annular rib, and an accommodation portion for a part of the plunger at which the helical rib is formed. The annular rib comprises a rib absent portion for guiding, to the accommodation portion, the helical rib reaching the annular rib as threaded engagement is advanced between the plunger and the gasket. The helical rib comprises an entrance-restricting terminal end portion for restricting the entrance of the helical rib into the rib absent portion after the part of the plunger 4 at which the helical rib is formed is stored in the accommodation portion 32 of the gasket.
