A medicinal-liquid administering device is for administering medicinal liquid filling a tubular body into a living body under a pressing action of a plunger. The medicinal-liquid administering device includes: a disposable part including: the tubular body, the plunger, and a movable part configured to be moved from an initial position and to press the plunger toward a distal-end side； a reusable part that is attachable to and detachable from the disposable part, the reusable part including: at least part of a driving part configured to move the movable part, a first position detection sensor configured to detect whether or not the movable part is at the initial position in a state before the movable part is moved, and an alarm part configured to output a first alarm when the first position detection sensor detects that the movable part is not at the initial position.
