[Purpose] We developed criteria for crawling motion analysis, for the purpose of understanding motor learning processes from changes in crawling motion, and investigated their reliability. [Subjects and Methods] Ten examiners (4 with experience, 2 novices, and 4 trainees) used a video recording of the crawling motion during 6-months to code the movements using the analysis criteria on two occasions. The reliability was ascertained using the levels of intra-and inter-examiner agreement, and the variation number. [Results] With the exception of the novices, the levels of agreement of the code and variation number were confirmed to be sufficiently reliable. The results also suggest that prior training increase the reliability.[Conclusion] The results suggest the method we have developed is objective.

[Purpose] The purpose of this study was to reconsider the crawling of infants by focusing on their repertoire.[Subjects] The subjects were 8 healthy infants aged 5-8 months who were using a Child Care Support Center.[Methods] The crawling of the infants on two types of floor (normal and unstable floor) was recorded on video, and analyzed for the motion of the head and trunk, the limbs, the movement of the center of gravity, and the driving force. The number of the repertoires of crawling was noted after agreement by three researchers.[Results] The repertories of crawling increased, and then decreased with experience of crawling.[Conclusion] Our results suggest that motor learning in infants' crawling progresses from random to rational movements, and that the process is repeated during development.