A blood component collection system (10) includes a first internal pressure calculation unit (110) adapted to calculate a first internal pressure of a first pressed portion (60) using first calibration curve data (118), a second internal pressure calculation unit (112) adapted to calculate a second internal pressure of a second pressed portion (62) using second calibration curve data (120), and a correction unit (114) adapted to correct the first calibration curve data (118) in a manner so that the first internal pressure becomes equal to the second internal pressure in a state in which operation of a collection and returning pump (100) is stopped during at least one of a collection operation and a returning operation of a first cycle.
