A microviable particle counting system includes: a microviable particle counting instrument configured to detect autofluorescence of a microviable particle in a sample as fluid, thereby counting the microviable particle in the sample; and a former-stage irradiator provided at a former stage of the microviable particle counting instrument to irradiate the sample with ultraviolet light. The ultraviolet light contains first ultraviolet light having such a wavelength that a carbon-carbon covalent bond is disconnected, and the first ultraviolet light has a wavelength shorter than 200 nm.