To obtain the subject new compound useful for prophylaxis and treat ment of cancers, etc., maintaining physiological activity, excellent in chemical stability and metabolic stability, by introducing a trifluoromethyl group into an indole parent nucleus of melatonin.

This compound is shown by the formula (R1 is a 1-4C alkyl or a phenyl which may contain a substituent group; R2 is H or a 1-4C alkyl) such as a compound capable of acting as a component melatonin agonist. The compound of the formula is produced, for example, by using melatonin (N- acetyl-5-methoxytryptamine), N-benzoyl-5-methoxy tryptamine or their derivative as a raw material and treating these compounds with an electrophilic trifluoromethylating agent.