There is provided a medicinal agent that is effective and highly safe for the prevention or alleviation of a peripheral nerve disorder that develops as a side effect occurring after the administration of an anti-cancer agent. The present invention relates to a novel medical use of an extract from inflamed tissues inoculated with vaccinia virus, and to a prophylactic or alleviating agent for a peripheral nerve disorder that contains the extract as an active ingredient. The agent containing the extract as an active ingredient is used for a prophylactic or alleviating agent for a peripheral nerve disorder induced by an anti-cancer agent and is a highly safe and remarkably highly useful medicinal agent with few side effects.