This invention provides to a novel pharmaceutical preparation for the treatment of gynecological diseases. The pharmaceutical preparation according to the invention comprises a therapeutic drug for the intrauterine, intravaginal or intrapelvic administration, or for the administration into the ovarian endometrioma, and a biodegradable polymer comprising a chemically modified hyaluronic acid or a salt thereof prepared by O-acylating, alkoxylating or crosslinking a complex of hyaluronic acid or a salt thereof and a cationic compound in a nonaqueous solvent. The preparation of the invention is preferably administered intrauterine, intravaginal, intrapelvic, and intratumor cavity.