An infusion state detection system (10) includes a liquid delivery pump (20) configured to deliver a medicinal solution inside the infusion line (12), and a pressure sensor (40) arranged in the infusion line (12) and configured to detect a pressure inside the infusion line (12). The liquid delivery pump (20) internally includes a control unit (54) configured to stop driving of the liquid delivery pump (20) and determine whether an infusion state is normal or abnormal on the basis of a pressure value detected by the pressure sensor (40) during the stop period in a case where the pressure value of the pressure sensor (40) becomes a threshold pressure value (Ps) for stopping liquid delivery or above.
