Vertical distribution of radiogenic heat generation is estimated for the Nissho granitic pluton emplaced in the upper crust of the Kuril arc. The estimated profile shows that heat generation steeply decreases with depth. Using the exponential model the thickness of the layer with relatively high heat generation is estimated to be 7¿2 km; this thickness is in the range of those estimated in heat flow provinces on continents. It is considered that this upward concentration of heat generation is caused by magmatic processes such as the gravitational differentiation in the magma chamber. In the upper crust of evolving arcs, where the continental-type crust is growing, magmatic processes in chambers of granitic magmas could be important for the upward concentration of heat generation. ¿ American Geophysical Union 1995