Abstract: A method of quickly predicting the degree of nodularity of spheroidal graphite cast iron from a molten iron sample is disclosed. The method comprises steps of reading out the lowest temperature T.sub.EU due to undercooling and the highest temperature T.sub.EM due to recalescence subsequent to the undercooling which occur at the time of eutectic solidification of a number of samples of molten iron for spheroidal graphite cast iron during cooling and solidifying under a predetermined cooling condition; reading out an elapsed time Z from the lowest temperature T.sub.EU to the highest temperature T.sub.EM ; determining constants a, b, c and e in the following formula which shows a relation between the values of the thus read out temperatures and the elapsed time and any of the characteristics D.sub.