This invention is directed to improve the electrostatic discharge strength and the latch-up strength of the semiconductor integrated circuit. To achieve the certain level of stable quality of the semiconductor integrated circuit by eliminating the variety in the electrostatic discharge strength and the latch-up strength is also aimed. The first NPN type bipolar transistor 3 and the second NPN type bipolar transistor 4 in the electrostatic discharge protection cell EC 1 are surrounded by the isolation region 6 made of the P+ type semiconductor layer and electronically isolated from other elements. The width WB1 of the isolating region 6 is larger than the width WB2 of the isolation region 7 that separates the elements comprising the internal circuit 50 from each other. This configuration can efficiently improve the electrostatic discharge strength and the latch-up strength. It is preferred that the width WB1 of the isolation region 6 is twice as large as the width WB2 of the isolation region 7 (usually, it is designed to minimize the size of the semiconductor integrated circuit) in order to efficiently improve the dielectric strength and the latch-up strength.