Abstract: A compound represented by formula (I); a process for producing a compound (substance F-1490) of formula (I), wherein X represents —O— and R represents a hydroxyl group, by using a microorganism belonging to the genus Cunninghamella; and a Cunninghamella sp. F-1490 strain (FERM BP-8287) capable of producing the substance F-1490; and an osteoclast differentiation inhibitory agent containing as an active ingredient the compound represented by formula (I): wherein X represents —O— or —CH2—, and R represents a hydroxyl group when X represents —O—, or a hydrogen atom when X represents —CH2—.