An object of the present invention is to provide a montelukast-containingcoated solid preparation that can be applied to one-dose package, wherein thehumidity stability of montelukast or a pharmacologically acceptable saltthereofcontained therein is maintained even when the preparation is unpacked. Thepresent invention provides a coated solid preparation containing as an activeingredient montelukast or a pharmacologically acceptable salt thereof andbeingcoated with a coating layer comprising polyvinyl alcohol and swelling clay,whereinthe mass ratio of the above-described polyvinyl alcohol to the above-describedswelling clay in the above-described coating layer is 8:2 to 3:7.
