The purpose of this study is to examine the effect of the lawn in a schoolyard on pupil's play. We observed the pupil's play in the schoolyard during the lunch break, and did the questionnaire for the fifth and the sixth grader of elementary schools which had the lawn in the schoolyard (=the lawn-school), and that which did not have the lawn in the schoolyard (=the non-lawn-school). As a result, the rate which pupils play in the schoolyard was higher in the lawn schools than the non-lawn-schools. And the rate which pupils “ romp ” in the schoolyard was higher in the lawn schools than the non-lawn-schools. Moreover, the movement in the action of“ romp” and “ rest ” in the lawn-schools were more various than the non-lawn-schools. And the frequency of some movements in these actions in the lawn-schools was higher in the lawn-schools than the non-lawn-schools. However, in other actions (for example, volleyball and soccer), there was no significant difference between the lawn-schools and the non-lawn-schools. From the above result, we considered that the lawn in the schoolyard became the factor which urges pupils to a play in the schoolyard. Moreover, we considered that the lawn in the schoolyard might activate a sport and the play in outside. Furthermore, we considered that the lawn in the schoolyard might increase actions touched the ground.