There is provided a biosensor, which may measure the concentration of indoor bioaerosols through an optical sensing method of sensing ultraviolet light scattered by bioaerosols, and an air cleaner having the same. The biosensor includes a light irradiator and an ultraviolet light sensor detecting scattered ultraviolet light, from light irradiated by the light irradiator, reflected from bioaerosols. The biosensor may measure the concentration of indoor bioaerosols through the optical sensing method in real time, using a certain wavelength of ultraviolet light scattered by bioaerosols, and may allow the air cleaner to be operated under proper conditions based on a measured concentration of bioaerosols and a measured concentration of dust particles.
