This study aimed to verify the achievability of various motor tasks using a children's ladder according to age level in preschool children, and to examine the relationship between motor tasks and fundamental motor ability. The subjects were 625 preschool children (300 boys and 325 girls) aged 4 and 5 years old. They performed nine kinds of ladder tasks and fundamental motor ability tests (20 meter dash, standing long jump, tennis-ball throw, and beam cross-jump). There are significant differences between the achievement rates of both age groups in all motor tasks. The 5 year old group showed higher values than the 4 year old group. The achievement rate of a quick skip was the low in both age groups. It was suggested that the relationship among motor tasks differs largely in both age groups from verifying correlations ; these figures being higher in the 5 year old group. Because the nervous system functions coordinating movement develops markedly between the ages of 4 and 5, this relationship may increase with age. Multiple correlations between the total score of motor ability and the nine ladder tasks were significant in both age groups (4 yrs : 0.547, 5 yrs : 0.502, p<0.05). It was suggested that the contribution of the “open-close jump” to the fundamental motor ability is substantial. Partial correlations for the “open-close jump”, “quick skip”, and “zigzag jump” were large in the 4 year old group. The scores for the “quick skip”, “twist jump”, and “lateral dash” were greater in the 5 year old group. It is therefore concluded that these motor tasks are effective in improving the coordination ability of today's children.