PROBLEM TO BE SOLVED: To provide medicines such as preventive or therapeutic agents for peripheral neuropathy by anticancer drug administration, preventive or therapeutic agents for neurodegenerative diseases or psychiatric disorders such as dementia, Alzheimers disease, Parkinsons disease, diabetic neuropathy, depression, glaucoma, and autism spectrum disorder, therapeutic agents for spinal cord injury, and analgesics for various pain diseases.SOLUTION: The invention provides medicines containing as an active ingredient trans-2-decenoic acid derivative represented by the formula (I), or a pharmaceutically acceptable salt thereof. (X is 1-pyrrolidyl, 3-thiazolidyl, piperidino, morpholino, 1-piperazyl, 1-azepanyl, and 1,4-diazepanyl and the like.)