Upon blood collection with a disclosed blood collecting apparatus 1, a part of a flow path adjacent to a suction drain mechanism 5 is filled with a liquid L different from the blood. A gas G is inserted in the flow path between the liquid L with which the part of the flow path adjacent to the suction drain mechanism 5 is filled and a target blood to be collected. The suction drain mechanism 5 pushes and pulls the gas G by pushing and pulling the liquid L during a standby time between collection and next collection, thereby controlling movement of the target blood. The suction drain mechanism 5 pushes and pulls the liquid L and the gas G during the standby time, whereby the target blood is continuously moved. This allows prevention of coagulation of the target blood in the flow path.
