An object of the present invention is to enable the repair and regeneration of articular cartilage, which could not be achieved by conventional therapies, and to provide a safe and inexpensive agent that is effective for the treatment of joint diseases such as osteoarthritis. According to the present invention, a combined formulation for simultaneously, separately, or sequentially administering a hyaluronic acid and an animal mucin-type glycoprotein for the treatment of joint diseases is provided.