This detection device is provided with: a chip including a detection region for detecting a substance to be detected; a light source which emits excitation light; a detector for detecting the fluorescence emitted from a fluorescent substance which labels the substance to be detected, and which is excited by the excitation light; and an optical fiber which includes a core, and a cladding covering the outer peripheral surface of the core, guides, to the detection region, the excitation light emitted from the light source, and guides, to the detector, the fluorescence emitted from the fluorescent substance. The optical fiber is fixed to the chip directly or via a connector. The excitation light emitted from the light source is guided within the core, and reaches the detection region of the chip. The fluorescence emitted from the fluorescent substance is guided within the core and the cladding, and reaches the detector.