Abstract: A neurocyte protective agent that is capable of alleviating mitochondrial dysfunction and oxidative stress in neurocytes is provided. The neurocyte protective agent and the agent for protecting neurodegenerative diseases according to the present invention comprise astaxanthin and/or an ester thereof. In particular, the neurocyte protective agent of the present invention is effective in protecting against the degeneration of dopaminergic neurons of the substantia nigra and noradrenergic neurons of the locus ceruleus, and it is expected that ingestion of the neurocyte protective agent will serve as fundamental therapy for Parkinson's disease.