Medical workers need to improve understanding of the pain of their child patients in order to offer effective treatments. For adults, it is difficult to express their pain verbally, so it can be expected more difficulty for children. Therefore, we have developed a Digital Pain Assessment-Tool (DPAT) that allows children to visually express (1) pain intensity and (2) pain cycle. In the present study, we conducted three experiments to compare the DPAT with an Analogue Pain Assessment-Tool (APAT) and a visual analogue rating scale (VAS), by applying quantitative and qualitative methods. The results showed the effectiveness and usefulness of the DPAT, especially by allowing communication of type of pain, which cannot be done with other tools. Also, the results showed improved pain intensity, easiness of use and user satisfaction. Moreover, the possibility of complementary use of the APAT and the SPAT was discussed.