An EP2 agonist which may have an EP3 agonistic effect has an effect of regenerating and/or protecting nerves, and is therefore useful as a therapeutic agent for a disease of the peripheral nervous system, such as a lower or upper motor neuron disease, a nerve root disease, plexopathy, thoracic outlet compression syndrome, peripheral neuropathy, neurofibromatosis and neuromuscular transmission disease. An EP2 agonist which has an EP3 agonistic effect is a safe and effective agent for the regeneration and/or protection of nerves which has little influence on the circulatory system.