A method for producing a solid preparation containing a compound represented by the formula (I) below or a pharmacologically acceptable salt thereof, which includes a step wherein a composition containing the compound represented by the formula (I) below or a pharmacologically acceptable salt thereof is mixed, while applying a mechanical stress to the composition. The compound of the formula (I) is as follows:The method results in improved dissolvability of the compound of the formula (I) or a pharmaceutically acceptable salt thereof.
