Abstract: Provided are a moisture detection method and a moisture detection system which are capable of detecting moisture in a simple manner. A moisture detection method in accordance with the present invention uses a moisture detection system which contains: (A) a substance that reacts with water to produce hydrogen peroxide; and (B) a fluorescent substance that is indirectly excited by hydrogen peroxide to emit light. The moisture detection system may further contain (C) a substance that reacts with hydrogen peroxide to produce a reaction product which excites the fluorescent substance (B) to emit light.