Provided is a weight measuring device which can ensure safety even in the event of problems such as the occurrence of faults or the reduction in measurement accuracy.Disclosed is a weight measuring device (10) which measures the weight of fluids used to purify blood. This measuring device (10) is provided with a first trunk body (110) equipped with a first installation unit (111) for installing a supplied liquid container (20), a second trunk body (120) connected to the first trunk body (110) and equipped with a second installation unit (121) for installing a filtered liquid container (30), a third trunk body (130) connected to the second trunk body (120), a first measuring instrument (220) whereby a total weight defined as the sum of the weight of the supplied liquid container (20) and that of the filtered liquid container (30) is measured from changes in the second trunk body (120) and is output as the first total weight, and a second measuring instrument (230) whereby a total weight is measured from changes in the third trunk body (130) and is output as the second total weight, and a warning unit (300) which generates a warning if the first total weight which is outputted and the second total weight which is outputted are different from each other by a value not lower than a specified amount.Linvention porte sur un dispositif de mesure du poids, qui peut garantir la sécurité même en cas de problèmes, tels que lapparition de défauts ou la réduction de la précision de la mesure. Linvention porte sur un dispositif de mesure du poids (10), qui mesure le poids de fluides utilisés pour purifier le sang. Ce dispositif de mesure (10) comporte un premier corps formant tronc (110), équipé dune première unité dinstallation (111) pour installer un récipient (20) pour liquide fourni, un deuxième corps formant tronc (120), relié au premier corps formant tronc (110) et équipé dune deuxième unité dinstallation (121) pour installer un récipient (30) pour liquide filtré, un troisi
