A liquid injection device (1) with a main body (4) having a cylindrical shape, an internal space (41) into which a plunger (5) is inserted and a supporting part (3) to which is fixed a liquid injection needle (10) which includes a hollow needle part (2) for injecting a liquid (8). The needle part (2) includes an anchoring part (22) that extends through the inside of the supporting part (3) and a puncturing part (21) that extends from the supporting part (3) for making a puncture in a living body. The puncturing part (21) has a distal side outer diameter equal to or greater than 0.1 mm and equal to or less than 0.25 mm, and a proximal side outer diameter greater than the distal side outer diameter.
