A smoke detector comprising: a first light emitting device, which is a LED configured to emit a light beam of a long wavelength; a second light emitting device, which is a LED configured to emit a light beam of a short wavelength; a long wavelength light emission driving circuit configured to drive the first light emitting device; a short wavelength light emission driving circuit configured to drive the second light emitting device; a long wavelength light receiving device and a short wavelength light receiving device configured to receive, at a different scattering angle for each light beam of the respective wavelengths, scattered light generated due to the light beams emitted simultaneously from the respective light emitting devices (14, 18) impinging on smoke, a first detection processing section configured to set a first driving condition configured to make the light emitting devices (14, 18) simultaneously emit light with a light emission current of the same current value, characterised by a second detection processing section configured to set a second driving condition configured to make the light emitting devices (14, 18) simultaneously emit light, wherein a light emission current of at least one of the light emitting devices (14, 18) is changed so that the light emission current is different from that of the other light emitting device, and a smoke type determination section configured to determine whether the smoke is smoke of a large particle diameter or smoke of a small particle diameter based on the reception signals from each light receiving device (16, 20) in each driving condition. a first light emitting device, which is a LED configured to emit a light beam of a long wavelength; a second light emitting device, which is a LED configured to emit a light beam of a short wavelength; a long wavelength light emission driving circuit configured to drive the first light emitting device; a short wavelength light emission driving circuit configured to drive the second light emitting device; a long wavelength light receiving device and a short wavelength light receiving device configured to receive, at a different scattering angle for each light beam of the respective wavelengths, scattered light generated due to the light beams emitted simultaneously from the respective light emitting devices (14, 18) impinging on smoke, a first detection processing section configured to set a first driving condition configured to make the light emitting devices (14, 18) simultaneously emit light with a light emission current of the same current value, characterised by a second detection processing section configured to set a second driving condition configured to make the light emitting devices (14, 18) simultaneously emit light, wherein a light emission current of at least one of the light emitting devices (14, 18) is changed so that the light emission current is different from that of the other light emitting device, and a smoke type determination section configured to determine whether the smoke is smoke of a large particle diameter or smoke of a small particle diameter based on the reception signals from each light receiving device (16, 20) in each driving condition.