A detection device comprises a chip holder, a light source, a light-guide rod, a wavelength separation filter, and an optical sensor. Given the relationship between the angle of incidence and light intensity of fluorescence on a light reception surface of the optical sensor, the optical transmittance of the wavelength separation filter at the dominant wavelength of the rays of fluorescence incident on the light reception surface at a peak angle of incidence at which the light intensity is the highest is greater than the optical transmittance of the wavelength separation filter at the dominant wavelength of the rays of excitation light incident on the light reception surface at the peak angle of incidence and is higher than the optical transmittance of the wavelength separation filter at the dominant wavelength of the rays of fluorescence incident on the light reception surface at an angle of incidence of 0 DEG.