The present invention relates to detection of defecation/urination of human bodies. In particular, the present invention provides a defecation/urination detection system and method using an RFID passive tag and a reader to measure a change in the sensitivity (or receiving count) of the tag and then inform a user of the incidence in real time mode. The defecation/urination detection system comprises: a first step of registering a defecation/urination detection tag in one-to-one correspondence upon receiving a request for registration of the defecation/urination detection tag, following the initiation a second step of detecting an energy level of a received signal that is generated from the registered defecation/urination detection tag, thereby detecting sensitivity based on the energy level and a third step of analyzing the detected sensitivity and then making an alarm sound and a display if there is a change in the sensitivity of the defecation/urination detection tag due to defecation/urination, regarding the change as a criterion for determination of the incidence of defecation/urination.
