The present invention relates to solubility improving preparation for enhancing the oral absorption of a poorly soluble drug, which is comprising (A) and (B)；(A) a granulated substance which comprises(i) a poorly soluble drug having an acidic group in the molecule,(ii) an alkaline agent,(iii) a surfactant,and this granulated substance dose not substantially contain a disintegrator, (B) a disintegrator existing only in the external of the granulated substance.
