To provide a lightweight aerated concrete capable of preventing irregularity and fluctuation of surface water repellency and waterproof property of the lightweight aerated concrete, giving no attachment of wet color by water and water absorption remains and excellent in beautiful appearance.

This lightweight aerated concrete includes a coated layer of a water repellant on the outer surface of a lightweight aerated concrete body which is mainly made from a siliceous raw material and a calcareous raw material and steam-cured at a high temperature and high pressure. The body has an absorption capacity of the diluted solution of the water repellant of not less than 70 g/m2 and the coated layer is formed by coating 2.1-20.0 g/m2 in terms of the effective component of a water repellant mainly composed of methyl hydrogen silicone represented by general formula shown below.