The solution of the problem to be solved is the provision of a means for determining timing both accurately and securely at which a treatment is shifted from gripping and coagulation (hemostasis or sealing) to resection by using a multifunctional treatment tool capable of exfoliation, gripping, coagulation (hemostasis or sealing) and resection of the treated region in a bipolar microwave treatment tool. A microwave surgical device control method and a device, in which the completion of coagulation (hemostasis or sealing) of tissue is detected and a microwave oscillation output is controlled by making use of the change in the direct current electric resistance value due to the reduction in the amount of water as the temperature rise of the tissue at the time of heating and coagulation of the tissue in the treated region with microwaves.
