The disclosed technology is directed to a treatment tool having a blade. The blade includes a treatment surface configured to engage with a treatment target. A heater is configured to be coupled to the blade. The heater includes respective first and second heat generating surfaces each of which extending in a direction transverse to the treatment surface. Respective first and second thermally conductive members each of which is interposed between the respective first and second heat generating surfaces and the blade so as to thermally engage the respective first and second heat generating surfaces and the blade to one another. The respective first and second thermally conductive members includes respective first and second thermal conductivity anisotropies each of which being higher in longitudinal directions of the blade and each of which being lower in widthwise directions of the blade that are transverse to the longitudinal directions.
