A light scattering type smoke sensor comprising a holder (5) with openings (9, 10) embedded with light emitting part (6) and light detecting part (7) respectively, which do not protrude into the smoke detection chamber (4). The optical axis (14) of light emitting part (6) intersects at a predetermined first angle alpha in the horizontal direction with the optical axis (15) of the light detecting part (7) at a predetermined second angle beta in the vertical direction. The optical axis (14) of the light emitting part (6) and optical axis (15) of the light detecting part (7) further comprise a configuration angle delta in the range of 90 SIMILAR 120 degrees used as the supplementary angle for the scattering angle &thetas;. Accordingly, the smoke detection part is further constituted in a thin-shaped light scattering smoke sensor which enables the setup of a scattering angle with no directivity in the smoke influx to the smoke detection chamber (4). <IMAGE>