An extracorporeal circulation device of the present invention implements extracorporeal circulation having high safety while suppressing increases in both the circuit scale and the power consumption. For this purpose, in the extracorporeal circulation device, a main control unit that is responsible for control of the whole device controls a motor drive circuit so as to yield a blood flow rate per unit time set by a user. The motor drive circuit applies a drive signal corresponding to the set blood flow rate to a motor. At this time, a sub-control unit configured by an FPGA detects the drive signal applied to the motor and keeps on monitoring whether or not the drive signal falls within an allowable range corresponding to the set blood flow rate. Furthermore, if the drive signal outside the allowable range is applied, the main control unit is deemed to be in an abnormal state and the main control unit is completely stopped. Then, the sub-control unit takes over the subsequent processing.
