In the method, a trione compound represented by the following formula (1) is (i) reduced by NaAlH2(OCH2CH2OCH3)2 and subsequently further reduced by a metal borohydride salt, or (ii) reduced by calcium borohydride, thereby producing an amide alcohol compound represented by the following formula (3) (wherein, R1 and R2 may be the same or different and each represents a hydrogen atom or a protecting group of an ureylene group; R4 represents an alkyl group, an aralkyl group, or an aryl group; and each of R5, R6, and R7 represents a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom).