The production method of a cooler includes a laminated material production step S1 and a brazing joining step. In the laminated material production step, a laminated material is formed by integrally joining a Ni layer made of Ni or a Ni alloy having an upper surface to which a member to be cooled is to be joined by soldering, a Ti layer made of Ti or a Ti alloy and arranged on a lower surface side of the Ni layer, and an Al layer made of Al or an Al alloy and arranged on a lower surface side of the Ti layer in a laminated manner. In the brazing joining step, a lower surface of the Al layer of the laminated material and a cooling surface of a cooler main body are joined by brazing.