A main object of the invention is to provide a novel useful vitamin D3 derivative, which has an excellent vitamin D3 activity and, as compared with conventional vitamin D3 derivatives, has a relatively small amount of influence on the systemic calcium metabolism. The invention includes a 9,10-secopregnane derivative of the following general formula [1] and a pharmaceutical composition containing it as active ingredient. In the general formula [1], the following partial structure between the 16-position and the 17-position means a single bond or a double bond: Y is a single bond, an alkylene, an alkenylene or phenylene; R1 and R2 are the same or different, each represents hydrogen, an alkyl or a cycloalkyl; or R1 and R2, taken together with the adjacent carbon atom, form a cycloalkyl; R3 is hydrogen or methyl; Z is hydrogen, hydroxy or —NR11R12.