PURPOSE: To obtain the titled device excellent in latch-up withstand voltage by a method wherein P+ type source-drain diffused regions or N+ type source-drain diffused regions are constructed of multilayers having lower concentrations in the outer periphery than inside.

CONSTITUTION: The P+ type drain diffused region 2 is composed of a P+ type high concentration region 2-a and a P type low concentration region 2-b having a concentration close to that of an N type substrate 1. In other words, a P+ type high concentration region 2-a similar to the conventional one is formed in the P type low concentration region 2-b. The P+ type source diffused region 3 is likewise composed of a P+ type high concentration region 3-a and a P type low concentration region 3-b. Besides, the N+ type source diffused region 6 and the N+ type drain diffused region 5 which have been formed in a P-well 7 substrate are constructed in such a manner that N+ type high concentration regions 5-a and 6-a are formed in N type low diffused regions 5-b and 6-b having concentrations close to that of the P-well substrate respectively.