Compounds of the general formula: ##STR1## wherein R.sub.1 represents a C1-10 alkyl group which may be substituted by one or more hydroxyl groups, R.sub.2 represents a hydrogen atom or a hydroxyl group, and R.sub.3 represents a hydrogen atom or a hydroxyl group; their intermediates; as well as synthesis processes of these compounds and intermediates are disclosed. The compounds of this invention, vitamin D derivatives substituted by sulfur atoms at the 22-position have a strong inhibitory effect against proliferation of keratinocytes.