The objective of the present invention is to provide a urine quantity measuring instrument which is highly portable and which can be handled easily by a patient him or herself, or by a user other than the patient. This urine quantity measuring instrument for measuring a quantity of accumulated urine in the bladder of a subject, by measuring the quantity of accumulated urine at a plurality of positions in an abdominal part in the vicinity of the bladder, is provided with: a probe which has a plurality of channels, and which transmits ultrasonic waves in each of the plurality of channels and receives ultrasonic wave echoes； a measuring unit which calculates a quantity of accumulated urine on the basis of the received ultrasonic wave echoes in each of the plurality of channels of the probe, and measures a channel pattern, which is information relating to the received channels； a maximum value position identifying unit which, on the basis of the quantities of accumulated urine measured by the measuring unit, identifies a combination of the quantity of accumulated urine at a maximum value position, which is the position at which the quantity of accumulated urine reaches a provisional maximum value, and the channel pattern； and a notifying unit which issues a notification for guiding the position of the urine quantity measuring instrument to the maximum value position, on the basis of the quantities of accumulated urine and the channel pattern measured by the measuring unit, and the quantity of accumulated urine and the channel pattern at the maximum value position identified by the maximum value position identifying unit.L'objectif de la présente invention est de fournir un instrument de mesure de quantité d'urine qui est très facile à transporter et qui peut être manipulé facilement par le patient lui-même, ou par un utilisateur autre que le patient. Cet instrument de mesure de quantité d'urine pour mesurer une quantité d'urine accumulée dans la vessie d'un sujet, par m
