A detection device (1) includes a light receiving unit (13a) which receives fluorescence a light receiving intensity calculation unit (32) which calculates light receiving intensity of fluorescence which is received by the light receiving unit (13a) while changing a relative position (L) between the light receiving unit (13a) and a test subject (100) and a specifying unit (33) which specifies an optimal position of the relative position (L) where the light receiving intensity which is calculated by the light receiving intensity calculation unit (32) becomes a maximum, and in which fluorescence is detected using the optimal position which is specified by the specifying unit (33).
