A fused heterocyclic compound or an N-oxide thereof represented by formula (1): wherein A 1 represents NR 7 or the like, A 2 and A 3 represent N or the like, Q represents O or S, R 1 represents a C1 to C6 chain hydrocarbon group or the like, R 2 and R 4 are the same or different and represent a hydrogen atom or the like, R 3 represents group J1, group J2 or group J3 of the following formulae: wherein R 3a , R 3b , R 3c and R 3e are the same or different and represent a C1 to C6 alkyl group optionally having one or more halogen atoms or the like; and R 3d and R 3f represent a C1 to C6 chain hydrocarbon group or the like; R 5 , R 6 and R 7 are the same or different and represent a C1 to C6 chain hydrocarbon group or the like; and n represents 0, 1 or 2, has an excellent control effect on pests.