Abstract. A fuzzy set A de ned on a probability space (;F;P) is calleda fuzzy event. Zadeh de nes the probability of the fuzzy event A usingthe probability P. We de ne the normal fuzzy probability on R usingthe normal distribution. We calculate the normal fuzzy probability forgeneralized trapezoidal fuzzy sets and give some examples. 1. IntroductionFour operations are based on the Zadeh’s extension principle([6]). Zadehde nes the probability of fuzzy event as follows.Let (;F;P) be a probability space, where denotes the sample space, Fthe ˙ algebra on , and Pa probability measure. A fuzzy set Aon is calleda fuzzy event. Let  A () be the membership function of the fuzzy event A.Then the probability of the fuzzy event Ais de ned by Zadeh([7]) asPe(A) =Z A (!) dP(!);  A (!) : ![0;1]:We de ned the normal fuzzy probability using the normal distribution andcalculated the normal fuzzy probability for quadratic fuzzy number([1]). Thenwe had the explicit formula for the normal fuzzy probability for trigonometricfuzzy number. Furthermore we calculated the normal fuzzy probability fortrigonometric fuzzy numbers driven by the above four operations([2]). Wede ne the generalized trapezoidal fuzzy set and calculate four operations oftwo generalized trapezoidal fuzzy sets([3]).In section 3, we correct the errors in the results for the normal fuzzy prob-ability for generalized triangular fuzzy sets([4]). In section 4, we calculate thenormal fuzzy probability for generalized trapezoidal fuzzy sets and give someexamples.