A medical treatment apparatus is an apparatus for treating a living body tissue by heating the living body tissue. The apparatus includes a heat transfer portion, a heating chip and a flexible substrate. The heat transfer portion is configured to come into contact with the living body tissue and transfer heat to the living body tissue. The heating chip is disposed on the heat transfer portion and is configured to heat the heat transfer portion. The flexible substrate is partly joined to a first surface of the heat transfer portion on which the heating chip is disposed, with a remaining portion extending outside the heat transfer portion. A heating trace for supplying power to the heating chip is formed on the flexible substrate.