A photoelectric smoke detector is provided which is suitable for being downsized without detection capability deterioration. The present invention relates to a photoelectric smoke detector for detecting presence of smoke by utilizing a light emitting element and a light receiving element whose optical axes intersect with each other. Then the photoelectric smoke detector has: a specialized labyrinth function fulfilling part for playing only a labyrinth function of bringing air flow into an interior space thereof and preventing entry of disturbance light into the interior space; and a smoke detecting part which is provided above the specialized labyrinth function fulfilling part so that an interior space of the smoke detecting part is communicated with the interior space of the specialized labyrinth function fulfilling part, and which has the light emitting element and the light receiving element built therein and has a small hole for extracting air flow that has passed through a detection area near an intersection between the optical axes of the light emitting element and the light receiving element.