It is an objective of the present invention to provide a pharmaceutical composition that can be used for an efficient administration of low-molecular weight drugs and polymeric compounds such as peptides and proteins by methods other than injection, and a method for producing the composition. The above-mentioned problem is solved by a pharmaceutical composition for transmucosal administration, comprising (a) a drug having a positive or negative charge at a predetermined pH, (b) a pharmaceutically acceptable small particle and (c) a pharmaceutically acceptable surface-coating polymer capable of being electrically charged at the pH, wherein the surface of the small particle is coated by the surface-coating polymer, the drug is immobilized on the surface of the small particle via the surface-coating polymer, and a complex is formed by a noncovalent interaction between the small particle and the surface-coating polymer and a concurrent electrostatic interaction between the surface-coating polymer and the drug.
