A cassette (50b, 50d) comprising a multiple bag mounted thereon, the multiple bag comprising: a first bag for reserving whole blood or a blood component; a filter having a filter medium for removing predetermined cells from a blood component obtained by centrifugation of the liquid contained in the first bag; a second bag for reserving a blood component obtained upon removal of the predetermined cells by the filter; a first tube for connecting the first bag and an inlet of the filter; a second tube for connecting the second bag and an outlet of the filter; a first clamp for closing and opening the first tube; and a second clamp for closing and opening the second tube, wherein the cassette (50b, 50d) holds a part of the first tube, a part of the second tube, the first clamp and the second clamp, and the cassette (50b, 50d) includes: a first clamp operating section for operating the first clamp, and a second clamp operating section for operating the second clamp, characterized in that the cassette (50b, 50d) includes a plate section that can be fitted to a unit body of an insert unit, the cassette (50b, 50d) is mounted in the centrifugation and separation apparatus through the insert unit, and the cassette (50b, 50d) includes two pins inserted into holes in the first bag and fixing an end of the first bag at an end portion on an outer side of the plate section, the two pins having an appropriate enlarged tip shape and being inserted in end holes of the first bag, thereby fixing an end portion of the first bag, the cassette further comprising an arch section for interconnecting both end portions on the outer side of the plate section, forming a bag hole together with the plate section, the first bag being inserted in the bag hole; and a filter holder connected to a central portion on an outermost diameter side of the arch section and holding the filter. a first bag for reserving whole blood or a blood component; a filter having a filter medium for removing predetermined cells from a blood component obtained by centrifugation of the liquid contained in the first bag; a second bag for reserving a blood component obtained upon removal of the predetermined cells by the filter; a first tube for connecting the first bag and an inlet of the filter; a second tube for connecting the second bag and an outlet of the filter; a first clamp for closing and opening the first tube; and a second clamp for closing and opening the second tube, wherein the cassette (50b, 50d) holds a part of the first tube, a part of the second tube, the first clamp and the second clamp, and the cassette (50b, 50d) includes: a first clamp operating section for operating the first clamp, and a second clamp operating section for operating the second clamp, characterized in that the cassette (50b, 50d) includes a plate section that can be fitted to a unit body of an insert unit, the cassette (50b, 50d) is mounted in the centrifugation and separation apparatus through the insert unit, and the cassette (50b, 50d) includes two pins inserted into holes in the first bag and fixing an end of the first bag at an end portion on an outer side of the plate section, the two pins having an appropriate enlarged tip shape and being inserted in end holes of the first bag, thereby fixing an end portion of the first bag, the cassette further comprising an arch section for interconnecting both end portions on the outer side of the plate section, forming a bag hole together with the plate section, the first bag being inserted in the bag hole; and a filter holder connected to a central portion on an outermost diameter side of the arch section and holding the filter. a first clamp operating section for operating the first clamp, and a second clamp operating section for operating the second clamp, characterized in that the cassette (50b, 50d) includes a plate section that can be fitted to a unit body of an insert unit, the cassette (50b, 50d) is mounted in the centrifugation and separation apparatus through the insert unit, and the cassette (50b, 50d) includes two pins inserted into holes in the first bag and fixing an end of the first bag at an end portion on an outer side of the plate section, the two pins having an appropriate enlarged tip shape and being inserted in end holes of the first bag, thereby fixing an end portion of the first bag, the cassette further comprising an arch section for interconnecting both end portions on the outer side of the plate section, forming a bag hole together with the plate section, the first bag being inserted in the bag hole; and a filter holder connected to a central portion on an outermost diameter side of the arch section and holding the filter.