A cell removal system (1) that is mounted on a centrifugal separator and removes predetermined cells from a body fluid, comprising:- a body fluid bag (10) that receives a body fluid；- a first body fluid component bag (11) that receives a first body fluid component having a relatively high cell concentration in the body fluid；- a second body fluid component bag (12) that receives a second body fluid component having a relatively low cell concentration in the body fluid；- a first channel (13) that connects the first body fluid component bag and the body fluid bag；- a second channel (14) that connects the second body fluid component bag and the body fluid bag；- a filter (15) that is provided in the first channel and removes predetermined cells from a body fluid component passing through the channel；- a first on-off valve (30) that opens and closes the first channel； and- a second on-off valve (31) that opens and closes the second channel,the first channel being connected to an end portion of the body fluid bag, the end portion being, when mounted on the centrifugal separator, on the side of a direction of centrifugal force by the centrifugal separator, andthe second channel being connected to an end portion of the body fluid bag, the end portion being, when mounted on the centrifugal separator, on the opposite side from the direction of centrifugal force by the centrifugal separator.
