A syringe assembly (10) is provided with a barrel (12) having a barrel tip portion (20), a puncture needle (14) projecting from the barrel tip portion (20), and a cap (16) that is detachably mountable to the barrel (12) so as to seal a distal end of a needle hole (28) . The cap (16) has a receiving hole (38) that receives the puncture needle (14), a bottom wall portion (36) into which the puncture needle (14) is inserted, and a stopper portion (48) that defines an insertion length of the puncture needle (14) relative to the bottom wall portion (36). In a state in which the cap (16) is mounted to the barrel (12), the length (L1) from the most proximal position of a contact region between the cap (16) and the puncture needle (14) to the most proximal position of an edge surface (30) is 1 to 3 mm.
