A drug solution administration apparatus (100, 200) comprising: an injection unit including an injection member that is configured to inject a drug solution into a living body; a delivery unit configured to be able to be coupled to and decoupled from the injection unit, the delivery unit including a delivery member that delivers the drug solution to the injection member, and a delivery device that delivers the drug solution stored to the delivery member; a control unit configured to control operation of the delivery device; and a controller configured to receive an input from a user and to operate the control unit, wherein the drug solution administration apparatus (100, 200) is configured to perform (i) a filling operation in which the drug solution is delivered from the delivery device to the delivery member, and (ii) an administration operation in which the drug solution is administered into the living body; characterized in that the drug solution administration apparatus (100, 200) further comprises a detection unit (140, 240) configured to detect a coupling state of the injection unit and the delivery unit, which is either a coupled state in which the injection unit and the delivery unit are coupled, or a decoupled state in which the injection unit and the delivery unit are decoupled; wherein the controller is configured such that, upon receiving an input from the user to perform the filling operation: the controller requests the coupling state detected by the detection unit (140, 240), from the control unit, upon determining that the injection unit and the delivery unit are in the decoupled state, the controller transmits a filling operation execution command to the control unit, and upon determining that the injection unit and the delivery unit are in the coupled state, the controller does not transmit the filling operation execution command to the control unit. an injection unit including an injection member that is configured to inject a drug solution into a living body; a delivery unit configured to be able to be coupled to and decoupled from the injection unit, the delivery unit including a delivery member that delivers the drug solution to the injection member, and a delivery device that delivers the drug solution stored to the delivery member; a control unit configured to control operation of the delivery device; and a controller configured to receive an input from a user and to operate the control unit, wherein the drug solution administration apparatus (100, 200) is configured to perform (i) a filling operation in which the drug solution is delivered from the delivery device to the delivery member, and (ii) an administration operation in which the drug solution is administered into the living body; characterized in that the drug solution administration apparatus (100, 200) further comprises a detection unit (140, 240) configured to detect a coupling state of the injection unit and the delivery unit, which is either a coupled state in which the injection unit and the delivery unit are coupled, or a decoupled state in which the injection unit and the delivery unit are decoupled; wherein the controller is configured such that, upon receiving an input from the user to perform the filling operation: the controller requests the coupling state detected by the detection unit (140, 240), from the control unit, upon determining that the injection unit and the delivery unit are in the decoupled state, the controller transmits a filling operation execution command to the control unit, and upon determining that the injection unit and the delivery unit are in the coupled state, the controller does not transmit the filling operation execution command to the control unit. the controller requests the coupling state detected by the detection unit (140, 240), from the control unit, upon determining that the injection unit and the delivery unit are in the decoupled state, the controller transmits a filling operation execution command to the control unit, and upon determining that the injection unit and the delivery unit are in the coupled state, the controller does not transmit the filling operation execution command to the control unit.