This liquid administration device (10) is provided with: an inner tube (1)； a needle tube (2)； a linking member (3)； an outer tube (4)； a plunger (11) that can assume a contracted first state and an extended second state； a first locking means that can maintain the first state of the plunger (11)； a second locking means (30) that can maintain the second state of the plunger (11)； and a cover member (6) that can move to a first position that restricts the needle tube (2) from puncturing a living body, and a second position at which the needle tube (2) can puncture the living body. In an unused state, the plunger (11) is maintained at the first state by means of the first locking means, and when the cover member (6) has moved from the first position to the second position from the unused state, the operation of the first locking means is released, and the plunger (11) enters the second state.
