Vehicle-mounted sensor, vehicle lamp, vehicle, and road surface state sensor

A road surface state sensor for detecting a state of water on a road surface, comprising:

• a light emission unit for emitting infrared light of a first wavelength range and infrared light of a second wavelength range into the road surface, a water molecule having respective different light absorption factors to the infrared light of the first wavelength range and the infrared light of the second wavelength range;
• a light detection unit for separately detecting the infrared light of the first wavelength range and the infrared light of the second wavelength range;
• a water detection unit for detecting whether a state of water on the road surface is a liquid phase or a solid phase on a basis of a difference between a light amount of the infrared light of the first wavelength range and a light amount of the infrared light of the second wavelength detected by the light detection unit, a difference between an absorption factor of water in the liquid phase to the infrared light of the first wavelength range and an absorption factor of the water to the infrared light of the second wavelength range, and a difference between an absorption factor of water in the solid phase to the infrared light of the first wavelength range and an absorption factor of the water to the infrared light of the second wavelength range;
• and
• an image processing unit for applying haze removal processing to each region of an image obtained by imaging a space outside the vehicle, on a basis of an amount of water in each region detected by the water detection unit.