Provided is a solubility-improving preparation for improving the oral absorbability of a poorly soluble drug, which is characterized by comprising: (A) granules each of which contains 1) a poorly soluble drug having an acidic group in the molecule, 2) an alkaline agent and 3) a surfactant and which contains substantially no disintegrating agent； and (B) a disintegrating agent which is present only in the outside of the granules.
