The purpose of the present invention is to provide a novel trans-2-decenoic acid derivative and a pharmaceutically acceptable salt thereof, and a medicament containing the compound described above as an active component and having a neurotrophic factor-like effect and a side effect reducing effect due to administration of anti-cancer agent which are highly safe. A trans-2-decenoic acid derivative or the pharmaceutically acceptable salt thereof, which is a compound of the present invention, is specifically represented by general formula (1) (where Y represents -O-, -NR-, or -S-, R represents a hydrogen atom, an alkyl group, a dialkylamino group, or the like, and W represents a substituent such as a dialkylaminoalkyl group), and is extremely highly useful as a preventive or therapeutic agent for dementia, Alzheimer's disease, Parkinson's disease, depression and the like, a therapeutic or repairing agent for spinal cord injury, or a medicament such as an agent for reducing the side effect due to administration of anti-cancer agent.