A control device is a control device for an energy treatment tool including a first holding member and a second holding member which hold a biological tissue, and a heating element configured to generate heat corresponding to supplied power, thereby heating a holding surface. The control device includes a temperature acquiring section that acquires a temperature of the heating element and a surface temperature estimating section that estimates, as a surface temperature, a temperature of at least a part of a surface of the first holding member which is different from a portion facing the second holding member, based on a change of the temperature of the heating element after supply of the power is stopped.
