A semiconductor integrated circuit includes: a well 35 of a first conductivity type formed on a substrate 37; a first external terminal 10, a second external terminal 11, and a third external terminal 12 provided above the substrate 37; a first protection circuit 20 provided on an electrical path between the first external terminal 10 and the second external terminal 11; a second protection circuit 21 provided on an electrical path between the second external terminal 11 and the third external terminal 12; and a third protection circuit 22 provided on an electrical path between the third external terminal 12 and the first external terminal 10. A guard ring 40 is formed continuously in the well to surround at least two circuits among the first, second, and third protection circuits 20, 21, and 22, formed on the well 35.