Numerical　estimation　for　the　flash　points　of　emulsi丘ed　fuels　were　made　on　the　basis　of　an　assumption　that emulsion　is　regarded　as　a　conjugate　solution　consisting　of　two　liquid　phases　which　are　partially　soluble　in　each other，Activity　coefficients　required　in　this　estimation　were　evaluated　by　UNIFAC　group－contribution　method． Using　this　method，the　flash　point　of　emulsified　fuels　can　only　be　estimated　from　the　literature　values． The　estimated　flash　points　tend　to　deviate　upwards　slightly，but　generally　agree　well　with　the　measured values　not only　for　the　higher　molar　fraction　values　but　also　for　the　lower　values　where　the　simple　estimation　with Raoult’s　law　is　not　available・The　mean　of　the　deviations　of　the　estimated　flash　points　from　the　measuτed　one were　L6℃for　whole　molar　fraction　values　and2．0。C　even　for　the　lower　values　than　O.9．