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