A syringe assembly (10) is provided with the following: an outer cylinder (12) having a cylinder tip (20) a puncture needle (14) that protrudes from the cylinder tip (20) and a cap (16) that seals the tip of a needle hole (28), the cap being detachably attached to the outer cylinder (12). The cap (16) has a storage opening (38) that stores the puncture needle (14), a bottom wall (36) into which the puncture needle (14) penetrates, and a stopper (48) that defines the depth to which the puncture needle (14) penetrates the bottom wall (36). With the cap (16) being attached to the outer cylinder (12), a length (L1) measured from the farthest base end position of the contact region between the cap (16) and the puncture needle (14), to the farthest base end position of an edge face (30), is 1-3 mm.
