The present invention provides a compound represented by the formula: wherein R1 is a C1-4 alkyl; R2 is (1) a 5- to 7-membered nitrogen-containing heterocyclic group which may have a substituent selected from the group consisting of (1′) a halogen, (2′) a hydroxy group, (3′) a C1-4 alkyl and (4′) a C1-4 alkoxy, (2) a phenyl which may have a substituent selected from the group consisting of (1′) a halogen, (2′) a C1-4 alkoxy-C1-4 alkyl, (3′) a mono-C1-4 alkyl-carbamoyl-C1-4 alkyl, (4′) a C1-4 alkoxy and (5′) a mono-C1-4 alkylcarbamoyl-C1-4 alkoxy, or the like; R3 is a C1-4 alkyl; R4 is a C1-4 alkoxy, or the like; n is an integer of 1 to 4; or a salt thereof, as a thienopyrimidine compound having gonadotropin-releasing hormone antagonistic activity.