To provide a blood component collector that can collect platelets efficiently and can obtain a high density liquid containing platelets.

The blood component collector 1 is a device for a blood component collecting circuit 2 provided with a rotor 142 having a blood storage space, a centrifugal separator 20 centrifugally separating the blood by the rotation of the rotor 142, the first line 21 connecting a blood drawing needle 29 and the inlet of the centrifugal separator 20, the second line 22 connected to the centrifugal separator 20, the third line 23 to inject an anticoagulant, the first tube 25a connected to the first line 21 and a plasma collection bag 25 connected to the second line 22, and a platelet collecting bag 26 connected to the second line 22. The blood content collector 1 is provided with a control section to control the number of centrifugal revolution of the rotor of the centrifugal separator, considering the speed of a blood stream of a blood donor at the time of collection.