A smoke detector includes: a housing; a sensing chamber in the housing, wherein in the sensing chamber, a first light emitter and a first light receiver that are disposed at the periphery of the sensing chamber and facing a middle portion of the sensing chamber are included, a first baffle is included in the sensing chamber, the first baffle is disposed adjacent to the first light emitter and includes a baffle body and a branch portion, the baffle body extends from the periphery of the sensing chamber toward the middle portion, and the branch portion comprises a plurality of sub-baffles branching off the baffle body; and a circuit board electrically connected to the first light emitter and the first light receiver respectively.