Abstract: A body fluid absorption object wetting alarm method and an apparatus associated are revealed. A light wavelength sensor is disposed on a body fluid absorption unit for detecting wavelength of the body fluid absorption unit. After the body fluid absorption unit becoming wet, the wavelength thereof changes. Then warning signals are sent to the receiving and checking unit. Thus, a caregiver at a management end of the receiving and checking unit knows that the body fluid absorption object worn by a care recipient was already wet and there is a need to replace the wet body fluid absorption unit with a new one immediately.