To provide a high speed rotation impeller capable of inhibiting the maximum stress generated at a disc, realizing a light weight of the disc and thereby enhancing a cost down and a responsiveness at the time of acceleration and speed reduction.

A disc part 2 has a hollow through hole 2a coaxial to a rotation center axis; a blade-mounting surface 2b connected to a blade part; and a disc back surface 2c axially opposite to the blade-mounting surface 2b. A cross section shape of the disc back surface 2c is determined such that the maximum stress is restricted and a volume is minimized. The cross section shape is also determined such that the maximum circumferential stress and the maximum radial stress become a permitted value or less by making a centrifugal force caused by own weight of the disc itself smaller. The cross section shape of this disc back surface 2c is recessed shape in which a radial intermediate part is recessed to the blade-mounting surface 2b side.