Upon blood collection with a disclosed blood collecting apparatus, a part of a flow path adjacent to a suction drain mechanism is filled with a liquid different from the blood. A gas is inserted in the flow path between the liquid with which the part of the flow path adjacent to the suction drain mechanism is filled and a target blood to be collected. The suction drain mechanism pushes and pulls the gas by pushing and pulling the liquid during a standby time between collection and next collection, thereby controlling movement of the target blood. The suction drain mechanism pushes and pulls the liquid and the gas during the standby time, whereby the target blood is continuously moved. This allows prevention of coagulation of the target blood in the flow path.
