A puncture needle connector (1) includes an outer cylinder (11), an inner cavity (1a) formed within the outer cylinder (11), an arm (15) provided at the outer cylinder (11), the arm (15) being elastically deformable by bending, and a claw (16) provided on the arm (15). The inner cavity (1a) is in communication with the outside via a first opening (21) and a second opening (22). When a puncture needle (210) is inserted into the inner cavity (1a) via a first opening (21), the claw (16) engages with an engagement structure (217) provided integrally with the puncture needle (210), a liquid-tight seal (25) is formed between an outer circumferential surface of the puncture needle (210) and an inner circumferential surface of the inner cavity (1a), and the puncture needle (210) and the second opening (22) are in communication with the each other.