Abstract：A seasonal probability prediction model for tropical cyclone (TC) genesis in the western North Pacific (5°-25°N, 110°-180°E) was developed using a simple logistic regression method. The predictors used in this model were total five: 850 hPa relative vorticity, 200-850 hPa vertical wind shear, 600 hPa relative humidity, 300 hPa equivalent potential temperature, and sea surface temperature (SST). Four predictors except for SST were obtained from differences of spatial-averaged value between May and January, and time average of Niño-3.4 index from February to April was used to consider the SST effects. As a result of prediction for the TC genesis from June to December during 1951 to 2007, years that the model forecasts are 21 years among the total 28 years when the observed TC genesis frequency was higher than normal year. The overall predictability was about 75%, and the model was also verified statistically through cross validation analysis using a method of the hindcast.