This detection device has a holder, light irradiation unit, angle adjustment unit, light receiving sensor, light receiving optical system, optical filter, and a control unit. The light receiving optical system guides light from a detection chip to the light receiving sensor. The optical filter is disposed in the light receiving optical system, blocks a part of plasmon scattered light, and passes, out of the light emitted from the detection chip, a part of the plasmon scattered light, and fluorescence emitted from a fluorescent material. The light receiving sensor detects the fluorescent light, and the part of the plasmon scattered light, which have been emitted from the detection chip and passed the optical filter. On the basis of the detection results of the plasmon scattered light, the control unit controls the angle adjustment unit, and adjusts the incident angle of the excitation light to a predetermined incident angle.