To reduce a longitudinal direction resistance between the source electrode and drain electrode of a high electron mobility transistor manufactured by a wafer by clearing the lattice misfit of the epitaxial wafer for the high electron mobility transistor.

In the epitaxial wafer W for the high electron mobility transistor having an electron supplying layer 3 of AlGaAs (aluminum gallium arsenide) or GaAs (gallium arsenide) and a channel layer 4 of InGaAs (indium gallium arsenide) on a GaAs substrate 1, a graded InGaAs electron supplying layer 7 or the same layer 8, in which an In composition is made gradually smaller from the channel layer 4 side toward the electron supplying layer 3 side, is provided between the electron supplying layer 3 and the channel layer 4.