A fluorescence sensor includes a detection substrate section, on a first principal plane of which a concave portion having a bottom surface parallel to the first principal plane is present and, on a side surface of the concave portion of which a PD element configured to receive fluorescent light and output a detection signal is formed, an LED element disposed on the bottom surface of the concave portion of the detection substrate section and configured to generate excitation light, and an indicator layer disposed on an inside of the concave portion on the LED element and configured to generate the fluorescent light corresponding to the excitation light and an analyte amount.