Abstract
This is a technical report for the structural properties of capsule-shaped void slab, which has been developed and introduced to actual buildings in order to eliminate beams at slab ceiling. This void slab has two characteristics. One is high void ratio to provide one of the lightest void slab in Japan. Two is its isotropy nature which enables to design variously outlined slab. Both are verified by the isotopic round shape voids around which concrete is easily cast against their narrow gaps contributing its high void ratio.