A liquid medicine injection device includes: a liquid medicine storage unit including a cylinder including a space configured to store liquid medicine therein and a discharge hole connected to the space, and a piston arranged inside the cylinder and moving toward the discharge hole depending on discharge of the liquid medicine； a first electrode on an outer surface of the cylinder； a second electrode on the outer surface of the cylinder, the second electrode facing the first electrode with the piston therebetween； and a circuit unit including a substrate electrically connected to the first electrode and the second electrode.
