A viable particle counting apparatus 77 includes devices 10, 70, 2. The device 10 radiates a light with a predetermined wavelength toward a liquid containing a detection target. The device 70 reduces a Raman-scattered light emitted from the liquid out of lights emitted due to an interaction of the light radiated by the device 10 with the target or the liquid and selects an autofluorescence light emitted from the target. The device 2 determines whether or not the target contained in the liquid is a viable particle, based on a light obtained after the Raman-scattered light is reduced by the device 70. The device 10 radiates the light with a wavelength that causes the autofluorescence light and the Raman-scattered light to be different in peak wavelength.