Control device for energy treatment tool, and energy treatment system

A control device for an energy treatment tool comprising a first holding member configured so that a holding surface comes in contact with a biological tissue, a second holding member that is configured to open and close relatively to the first holding member to hold the biological tissue between the first holding member and the second holding member, and a heating element configured to generate heat corresponding to supplied power, thereby heating the holding surface, the control device comprising:

• 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.