The present invention provides a compound which functions as a selective vitamin D receptor modulator and has action-selectivity or tissue-selectivity such that it does not induce hypercalcemia but causes other effects. There is provided a compound represented by formula (I), a solvate thereof or a prodrug thereof.wherein m and n each independently represent 1 or 0；R represents a hydrogen atom or an alkyl group；Y represents an ethane-1,1-diyl group or an ethyne-1,2-diyl group； andZ1 represents a hydrogen atom and Z2 represents a hydroxyalkoxy group, orZ1 and Z2 jointly form a methylene group.
