The group of inventions relates to the field of fire alarm tools. A smoke detection device comprises a housing, and a control unit with a power unit and a scattered light sensor connected thereto are arranged within the housing, and the sensor consists of an optical chamber having a first emitter, a second emitter and a photoreceiver arranged therein. The optical chamber is surrounded by a filtering chamber having output openings provided therein, the openings are coupled to the optical chamber via a labyrinth that terminates with a ring slit that is provided between the optical chamber and a filtration chamber along a circumference of the optical chamber. The control unit is configured to constantly providing power impulses to the first emitter, as well as to connect the second emitter to the power unit at a moment when a threshold signal arises at the photoreceiver, to determine levels of signals of the photoreceiver which arise during a successive providing of the power impulses to the first and the second emitters, as well as to form the alarm signal if the signal level of the photoreceiver within the second emitter connection period is at least 20% greater than the signal level of the photoreceiver within the first emitter connection period, which defines the claimed operation method of the device. Therewith, the scattered light sensor is configured such that the first emitter has a wavelength of 940nm+/-5% and generates an emission in a cone having a solid angle of maximum 5 degrees, the second emitter has a wavelength of 470nm+/-5% and generates an emission in a cone having a solid angle of maximum 9 degrees, and the photoreceiver has a sensitivity range from 400 nm to 1100 nm. Therewith, the emitters and the photoreceiver are arranged along a circumference of the optical chamber with an angle of 15+/-2 degrees formed between an optical axis of each of the emitters and a horizontal plane, an angle of 23+/-2 degrees formed between optical axes of the first and second emitters, and an angle of 22+/-2 degrees formed between an optical axis of the photoreceiver and the horizontal plane.