To provide a MOSFET element, which suppresses its drift resistance and has a low on-resistance for its high breakdown voltage, and the manufacturing method of the MOSFET element.

In a MOSFET element of a constitution, wherein epitaxial layers are provided between sources 4 and a drain (substrate 1) and the on- resistance of the element to the breakdown voltage of the element is decided in unique manner according to the doping concentrations in the epitaixal layers, the doping concentrations in the epitaxial layers are increased so that an on- resistance with respect to a breakdown voltage VB is reduced, and the MOSFET element is constituted of the first epitaxial layer 21 of a thin layer thickness and the second epitaxial layer 22, having a low doping concentration and a thick layer thickness.