Smoke detector

A smoke detector 1 according to one embodiment of the present invention includes a housing 11 and a smoke detection unit 13 housed in the housing 11. The smoke detection unit 13 has a sensor 131 that detects smoke in the air, an intake section 132 connected to an intake pipe 7, and an exhaust section 133 connected to an exhaust pipe 8. The smoke detection unit 13 is held in the housing 11 in either a first arrangement direction in which the intake section 132 is on the upper side or a second arrangement direction in which the intake section 132 is on the lower side, depending on the positions of the intake pipe 7 and the exhaust pipe 8. The housing 11 has a piping hole H1 through which the intake pipe 7 passes and a piping hole H2 through which the exhaust pipe 8 passes when the smoke detection unit 13 is held in the first arrangement direction. The housing 11 also has a piping hole H3 through which the intake pipe 7 passes and a piping hole H4 through which the exhaust pipe 8 passes when the smoke detection