PROBLEM TO BE SOLVED: To provide a substrate concrete surface adjustment method for forming a sound coated floor while maintaining good adhesiveness over a long period without causing swollenness in various floor coating materials applied onto a coating material composition due to moisture supplied from a substrate concrete, and to provide a substrate concrete floor construction method applying the same.SOLUTION: The substrate concrete surface adjustment method includes spraying water on the surface of the substrate concrete, and applying a water-based epoxy resin mortar composition of 0.5-2.7 kg/m, containing hydraulic cement, aggregate and a water-based epoxy resin, onto the substrate concrete having no floating water on the surface, the water-based epoxy resin mortar composition being a coating material composition in which the weight ratio of the hydraulic cement to water is 0.3-0.4, the weight of a resin solid component of the resin is 4-10% of the weight of all compound containing the water when the res
