A droplet in an airstream deforms and disintegrates into finer droplets by a complicated mechanism. We focus on bag-type and umbrella-type breakup mechanisms in the present study. Under conditions in which the relative velocity between a droplet and the airstream is low, the droplet breakup mechanism changes from bag-hype to umbrella-type breakup with a small increase in the relative velocity. The airflow around a single deformed droplet was visualized and the velocity distributions were measured by particle image velocimetry. The droplet velocity was measured by high-speed video. The experimental results show that vortices are generated on the leeward side of the droplet. For the bag-type breakup, the vortices are generated alternately, similar to a Karman vortex. For the bag-type breakup, the upward air velocity toward the leeward surface of a droplet is less than the downward air velocity toward the windward surface. The relative velocity between the upward and downward air velocities bulges the droplet out like a bag. On the other hand, for the umbrella-type breakup, bilaterally symmetrical twin vortices are generated. The upward velocity is almost the same as the downward velocity. Therefore, the center of the droplet remains as a wick and the peripheral part of the droplet bulges out.