PURPOSE: To form the FET capable of rapidly operating at low cost collectively and evenly in wide space.

CONSTITUTION: The Junction type field effect transistor is provided with a substrate 1 having a crystal formation starting point comprising non-single crystalloid, a III-V group compound single crystal having a p type semiconductor region 104 formed on a substrate 101 using the starting point as a nucleus by crystalline formation process as wall as an n type semiconductor region 105 on the p type semiconductor region 104 or an insular semiconductor crystal as a III-V group semiconductor polycrystalline in the mean particle diameter exceeding 0.2μm. Furthermore, the FET is provided with source, drain electrodes 107 having ohmic junction formed on the n type semiconductor region 105 as well as a gate electrode 108 having Schottky junction formed on the n type semiconductor region 105.