A urine amount estimation device 100 is provided with: an ultrasonic sensor 1 for transmitting ultrasonic waves into a body and detecting reflected waves of the ultrasonic waves； and an estimation unit 52 for estimating the amount of urine in the bladder on the basis of the presence or absence and/or the magnitude of reflected waves W3 from the bladder, said reflected waves W3 being detected by the ultrasonic sensor 1.尿量推定裝置100具備：超音波感測器1，其向體內發送超音波，並檢測超音波的反射波；以及推定部52，其根據是否有由超音波感測器1檢測出的來自膀胱的反射波W3及/或由超音波感測器1檢測出的來自膀胱的反射波W3的大小來推定膀胱中的尿量。
