Recent surveys show that almost all massive stars are born in binary systems. From the fact that these massive stars are the progenitors for core-collapse supernovae, the majority of these events should be occuring in binaries. When a star explodes in a binary, the companion may be affected by the supernova ejecta, possibly changing the further evolution of the binary. In this talk I will introduce results of hydrodynamical simulations of supernova ejecta hitting a star in massive binaries. We focus on the mass removed and its dependences on parameters. I will also show its application on a real supernova, iPTF13bvn, and our prediction on the possible observational features of the companion star.