Novel 4-(3-butynyl)aminopyrimidine derivatives represented by general formula [I] are useful as pest control agents. In general formula [I], R1 is a mono- or bi-cyclic ring which may contain 0 to 3 heteroatoms, for example, phenyl or oxazolyl; R2 is a hydrogen atom, —R, —OR, —C(O)OR, —C(O)NHR, —CONR2 (wherein R is straight-chain or branched C1-8 alkyl, or the like), hydroxyalkyl, or the like; R3 is a hydrogen atom, a halogen atom, acyloxy represented by (straight-chain or branched C1-8 aliphatic hydrocarbon group) —CO—O—, or the like; and R4 is a hydrogen atom, a halogen atom, C1-6 alkyl, or the like, or alternatively, R4 and R3 together with the carbon atoms on the pyrimidine ring may form a thiophene ring, a pyrrole ring, an imidazole ring, a benzene ring, a pyrimidine ring, a furan ring, a pyrazine ring, or a pyrrolidine ring.