A drug solution administration device comprising: a drug solution reservoir that is filled with a drug solution; a plunger member that pushes out the drug solution filled in the drug solution reservoir; a plunger operation portion that operates a movement of the plunger member; a drive unit that applies a drive force to the plunger operation portion; a rotation detection unit that detects a rotation sensor value which is the number of rotations of a rotating body connected to the drive unit when a drive signal for one rotation is output to the drive unit; a control unit that detects blockage of a flow path through which the drug solution is sent out based on the rotation sensor value detected by the rotation detection unit and controls the drive unit; and characterized in that said drug solution administration device comprises a storage unit that stores a blockage detection threshold value which is a threshold value of the rotation sensor value when the control unit detects blockage and a blockage start threshold value set to a value closer to a normal value of the rotation sensor value detected by the rotation detection unit in a state in which the flow path is not blocked than the blockage detection threshold value, and the control unit counts the number of rotations of the drive unit from when the rotation sensor value reaches the blockage start threshold value until the rotation sensor value reaches the blockage detection threshold value, detects blockage of the flow path when the rotation sensor value reaches the blockage detection threshold value, and rotates the drive unit in a direction opposite to a direction in which the drug solution is administered based on the counted number of rotations. a drug solution reservoir that is filled with a drug solution; a plunger member that pushes out the drug solution filled in the drug solution reservoir; a plunger operation portion that operates a movement of the plunger member; a drive unit that applies a drive force to the plunger operation portion; a rotation detection unit that detects a rotation sensor value which is the number of rotations of a rotating body connected to the drive unit when a drive signal for one rotation is output to the drive unit; a control unit that detects blockage of a flow path through which the drug solution is sent out based on the rotation sensor value detected by the rotation detection unit and controls the drive unit; and characterized in that said drug solution administration device comprises a storage unit that stores a blockage detection threshold value which is a threshold value of the rotation sensor value when the control unit detects blockage and a blockage start threshold value set to a value closer to a normal value of the rotation sensor value detected by the rotation detection unit in a state in which the flow path is not blocked than the blockage detection threshold value, and the control unit counts the number of rotations of the drive unit from when the rotation sensor value reaches the blockage start threshold value until the rotation sensor value reaches the blockage detection threshold value, detects blockage of the flow path when the rotation sensor value reaches the blockage detection threshold value, and rotates the drive unit in a direction opposite to a direction in which the drug solution is administered based on the counted number of rotations.