PURPOSE: To obtain a sheet with improved corrosion resistance for a heat exchanger made of Al by using Al alloys each having a specified composition as the materials of an inner layer, a core material layer and an outer layer and by making the potential of the core material layer higher than the potential of the inner layer.

CONSTITUTION: A sheet for a heat exchanger made of Al is composed of an inner layer, an intermediate core material layer and an outer layer. The core material layer is made of an Al alloy contg. 0.2W0.6% Cu, a prescribed amount of one or more among Si, Fe, Mn and Mg, and inevitable impurities. The inner layer is made of an Al alloy contg. a much smaller amount of Fe and one or more among Cu, Mn, Mg, Zn and Ti than the Al alloy of the core material layer, and the outer layer is made of an Al alloy contg. 5W13% Si. The potential of the core material layer is made higher than the potential of the inner layer by ≥about 50mV, so the corrosion of the core material is effectively prevented.