To achieve an analyzer for analyzing and operating a small sample such as DNA compactly and inexpensively.

An analyzer 1 incorporates an optical system for measuring fluorescence from a sample that travels in a small channel 24c. Concretely speaking, a light source for generating light for exciting the fluorescence of the sample and a light guide (light-guiding means) for guiding light from the light source into the small channel 24c are provided, thus appropriately exciting the fluorescence of the sample of the small channel 24c. Then, for observing the fluorescence of the sample, a condensation optical element 26 for capturing fluorescence from the sample and a sensor part 11 are provided on the wall surface of the small channel 24c, thus appropriately observing the fluorescence of the sample in the small channel 24c.