The production of disposable diapers is rising due to an increase in number of elderly people who require nursing care. When providing diaper care, it is difficult to know remotely the time of urination and amount of urine absorbed by a diaper. Hence, a remote sensor system that automatically records the time and amount of urine in a diaper is being developed. In this study, a digital capacitive sensor system was developed to estimate the amount of diaper absorption. Preliminary and phantom experiments were conducted to investigate the basic performance of the developed system. We also measured the amount of urination of two subjects using the developed system. A phantom, a waist-type torso mannequin filled with saline solution, and two male subjects wore pad-type diaper on the inside and tape-type diaper on the outside. Electrodes were attached to the outer surface of the tape-type diaper to measure the change in capacitance caused by urination. In the preliminary experiment, the developed system measured capacitors with known capacitance within 5.47% error. In the phantom experiment, the change in capacitance decreased as the amount of pseudo-urine absorbed by the pad-type diaper increased. Moreover, the results of human subjects urinating five times were consistent with the results of the preliminary experiment. Therefore, remote and quantitative evaluation of the urine absorption volume was possible using the developed digital system.