A blood collection device having a blood-collecting tube, a needle, a blood container connected to the needle by the blood-collecting tube. The blood container has a blood-storing space containing anticoagulant solution. Two blood-component containers and an erythrocyte-preserving solution container are connected to the blood container by a blood-component supplying tube and a tube. The containers are made of soft material. A branching member is coupled to the blood-collecting tube and located between the blood container and the needle. A tube branching from the blood-collecting tube is connected to a filter. The filter allows passage of gas but substantially prevents passage of blood, bacteria, microorganism and the like. A flow stopper connects the blood-collecting tube to the filter. The flow stopper comprises a breakable member closing the branch tube. When the breakable member is broken, the branch tube communicates with the filter.