A drug solution administration device includes: an injection unit configured to inject a drug solution in vivo; a container; a push-out mechanism configured to allow the drug solution stored inside the container to flow into the injection unit; a sealing member attached to the push-out mechanism and pressed against a wall surface of the containing space; a drive mechanism configured to generate a drive force for moving the push-out mechanism back and forth; and a control unit is configured such that, when a predetermined time has passed after the control unit controls the drive mechanism to stop operation of the drive mechanism, the control unit controls the drive mechanism to move the push-out mechanism and to shift a position of the sealing member relative to the wall surface of the containing space.
