We derived initial mass functions (IMF) of massive stars in three different regions of spiral arms within 2.5kpc from the sun. The derived IMF slope β β of Local arm stars is found to be −2.09∼−2.06 −2.09∼−2.06 , very close to that of Bisiacchi et al. (1983). For Sagittarius-Carina arm stars β β ranges from -1.77 to - 1.72 which is close to that of overall stars given by Germany et al. (1982). Possible causes inducing the regional difference in IMFs are discussed.