A syringe assembly includes a barrel having a barrel tip portion, a puncture needle projecting from the barrel tip portion, and a cap that is detachably mountable to the barrel so as to seal a distal end of a needle hole. The cap has a receiving hole that receives the puncture needle, a bottom wall portion into which the puncture needle is inserted, and a stopper portion that defines an insertion length of the puncture needle relative to the bottom wall portion. In a state in which the cap is mounted to the barrel, the length from the most proximal position of a contact region between the cap and the puncture needle to the most proximal position of an edge surface is 1 to 3 mm.
