Microwave hyperthermia treatment device includes a microwave generation unit, a power supply unit, and a control unit including an exposure-time actuation timer, an intermittent actuation timer, a second-device connecting terminal, and a remote switch. Two microwave hyperthermia treatment devices are connected with each other via the second terminal connecting terminals for simultaneous use flanking the torso along either side of an affected area, whereby superposed strong microwaves are irradiated. The temperature of tumor(s) in the affected area can thereby be brought to about 43.degree. C. in about 1 minute, rendering lengthy treatment periods unnecessary and thus alleviating temperature stress on the patient. Two remote-control switches to the control unit can be provided, one of which may be given to a patient for use as an emergency stop switch, eliminating the necessity of having to insert a temperature sensor in the body, which also alleviates the burden on the patient.