Massive stars are fundamental in determining the appearance and evolution of galaxies. For studying the Galactic rotation curve and earlier phase of massive star forming process, three massive star forming regions are selected. The Galactic rotation curve can be constrained with the rotation speed of stars and gas because massive stars and their associated molecular clouds trace the spiral arms of The Galaxy. I will introduce the VERA system and the results of the first astrometric observations toward three massive star forming regions. And, by using the results of the measurements of parallaxes and proper motions, constrain the rotation curve of outer galactic plane and discuss about earlier phase of stellar evolution in massive star forming regions.