When detecting fluorescence of a bead chip array, reflected light from a bead is detected at the same time, so as to recognize the bead position. The reflected light can be detected in a similar manner for all beads, regardless of the presence or absence of a fluorescent substance. If the positions of all beads are detected, accurate detection can be achieved by quantifying only the fluorescence at the detected positions. The fluorescence wavelength alone is detected by a first detector using a wavelength selection filter. Other wavelengths are detected by a second detector, thereby obtaining the reflected light. Data on the reflected light is processed into an image for obtaining the bead profile, the bead position is recognized by detecting the center position based on the profile, and the fluorescence is quantified based on the bead position.