The present invention provides a curable composition excellent in rubber elasticity, coating film strength, coatability, and adhesion to a waterproof base and the like. The curable composition of the present invention contains a polyalkylene oxide having a hydrolyzable silyl group, and feldspars having an average particle diameter of 0.01 to 100 μm, and preferably further contains calcium carbonate. The feldspars may preferably contain nepheline syenite. The curable composition can form a cured product having excellent rubber elasticity and coating film strength, and excellent adhesion, while being low in viscosity and excellent in coatability.