A compound represented by the following formula (1): wherein R 1 is an aldopyranose residue wherein the 6-hydroxyl group is optionally alkylated, R 2 is a C 1-26 hydrocarbon group optionally having substituent(s), R 3 is a hydrogen atom or a C 1-26 hydrocarbon group optionally having substituent(s), R 4 is a C 1-21 hydrocarbon group optionally having substituent(s), X is an oxygen atom or -CH 2 -, and Y is -CH 2 -, -CH(OH)- or -CH=CH-, or a salt thereof is useful for the prophylaxis or treatment of cancer or infection, since it can preferentially induce production of IFN-³ of NKT cells.