An object of the present invention is to provide an oral solid preparation that can be produced in a simpler manner than conventional methods, that exhibits high bioavailability and high dissolubility even in persons having low stomach acid, and that can also ensure dissolubility after being allowed to stand for a certain period of time. Another object is to provide a simple method for producing the oral solid preparation. The present invention relates to an oral solid preparation comprising, as an active ingredient, a finely milled crystal obtained by milling an aripiprazole hydrate crystal, and a pharmaceutically acceptable carrier, the finely milled crystal having a mean particle size of 15 μm or less an oral solid preparation comprising, as an active ingredient, a finely milled powder obtained by milling a highly hygroscopic aripiprazole anhydrous crystal, and a pharmaceutically acceptable carrier, the finely milled crystal having a mean particle size of 10 μm or less a method for producing an oral solid preparation comprising the steps of (1) milling an aripiprazole hydrate crystal into a finely milled crystal having a mean particle size of 15 μm or less, and (2) mixing the obtained finely milled crystal with a pharmaceutically acceptable carrier and a method for producing an oral solid preparation comprising the steps of: (1) milling a highly hygroscopic aripiprazole anhydrous crystal into a finely milled powder having a mean particle size of 10 μm or less and (2) mixing the obtained finely milled powder with a pharmaceutically acceptable carrier.La présente invention a pour objet une préparation solide à usage oral qui peut être produite dune manière plus simple quavec les procédés classiques, qui présente une haute biodisponibilité et une haute dissolubilité même chez des personnes ayant une faible acidité stomacale et qui peut également assurer la dissolubilité après avoir été laissée au repos pendant un certain temps. Linvention a pour autre objet un procé
