PURPOSE: A ceiling and a construction method of a ceiling are provided to ensure soundproof performance and safety from fire by heat resistance by a light aerated concrete block. CONSTITUTION: A construction method of a ceiling is as follows. A plywood form(41) is formed between walls, a yoke(42) and a joist(43) are respectively installed to cross. The lower parts of the yoke and the joist are supported by a support(44). A thin light aerated concrete block(51) is installed on the upper end of the wall as a slab deck. A trapezoidal cutout unit(52) is formed on the upper ends of both sides of the light aerated concrete block. A large trapezoidal cutout unit is formed on the coupling unit of two light aerated concrete blocks. A plurality fixing units(54) are inserted into horizontal holes(53) on the floor of the large trapezoidal cutout unit.
