Balloon-based Operation Vehicle (BOV) is currently developed at JAXA for the realization of microgravity environment. As for this research, second experiment of 2006 and third experiment of 2007 are already planned. As a member of the control and electric system group, we estimate a method to detect the relative position of an integumentary covering as an inner shell of an experimental device with laser sensors. In this paper is explained a summary of a microgravity experimental device and shown it about an experiment performed in May, 2006.