Provided is a paper diaper which is safe to a wearer thereof and also has additional values of, for example, developing a plurality of colors and providing a practical effect of instantaneously detecting that the wearer has urinated, or the like. In a paper diaper 11 including a back sheet 13 for covering an outer side of an absorption body 14 for absorbing urine, an indicator portion 15 containing a colorless color-developing agent formed of an electron-donating coloration compound is formed by application on a wide range of an inner surface of the back sheet 13, and a color development assisting agent 16 is provided on the indicator portion 15. The color development assisting agent 16 is dissolved in the urine to contact the indicator portion 15, thus to cause the indication portion 15 to develop a color.
