This study investigated the developmental changes in head movement during stepping in toddlers. The subjects were 39 toddlers aged 4 to 6 years, and 13 adults aged 19 to 22. Vertical and horizontal head movements during ordinary stepping were measured with a position-sensor. The length of head movement for 1024 points of A/D converted data at 20.48 sec intervals was calculated as an index of magnitude for each of the 2 types of vertical and horizontal movements. Results were as follows: (1) The horizontal magnitude was nearly equal between 4 and 5years, and significantly decreased at 6years. (2) The vertical magnitude didn't change from 4 to 6years.