A treatment device which applies energy to a biological tissue to treat the biological tissue, includes: an interlocking mechanism that regulates at least one of a closing time until first and second jaws reach a closed state from an opened state when one operation is input into an operating body for a handle, and a unit closing amount from the opened state toward the closed state, interlocks at least one of the first and second jaws with the operating body, and is interposed between the operating body and the handle and an elastic member that is disposed in the interlocking mechanism, couples the operating body with the handle, pulls the operating body toward the handle at a constant load or a constant pressure, and regulates the closing time until the closed state is reached from the opened state.
