Provided is a blood component collection cassette capable of measuring a circuit internal pressure using a simple and economical configuration.A blood component collection cassette (28) includes an inflow line for sending blood or a blood component collected from a donor to a centrifugal separator (14), a return line for returning a predetermined blood component to the donor, and a line forming member forming one of the inflow line and the return line and having a load detection soft portion made of a soft material.
