A complementary field effect element develops an intensified latch-up preventive property even if the distance between the emitters of parasitic transistors is short, and a method of producing the same are disclosed. The complementary field effect element includes a high concentration impurity layer (16) formed by ion implantation in the boundary region between a P-well (2) and an N-well (3) which are formed adjacent each other on the main surface of a semiconductor substrate (1). Therefore, carriers passing through the boundary region between the P-well (2) and the N-well (3) are decreased, so that even if the distance between the emitters (4, 5) of parasitic transistors is short, there is obtained an intensified latch-up preventive property.