A detection system for a toilet unit for use in a supine position is provided, in which a treating body formed in a substantially T-shape by a urination and defecation container serving as a lateral casing and a washing nozzle retainer serving as a vertical casing is formed in a boat shape, the washing nozzle retainer is held in the crotch of patient's legs to enable the patient to urinate and defecate within the urination and defecation container, an injection nozzle provided at a head section of the urination and defecation container is provided to be capable of crushing and conveying the stools, and a nozzle provided on the washing nozzle retainer is adapted to wash the private parts of the patient, wherein a water level sensor installed at a side edge section of the urination and defecation container on the upstream side detects water rising due to wash water and water from the injection nozzle and controls to forcibly discharge the urination and defecation out of the urination and defecation container when the water reaches a certain level.