The upsetting accidents on small vessels caused by the wind and wave have happend of ten times in recent years in our country. When we are to certify the safety of small vessels, the heeling moment due to the wind pressure is one of the most important factors. This paper deals with the results of wind-tunnel experiments in which the author has measured the heeling moment as well as the force due to wind pressure on three typical small vessels with the dynamometers of the magneto-striction type. The meassured values of heeling moment are larger than those which were hitherto estimated generally from calculation.