To obtain the subject preparation containing a hydroxamic acid derivative, having a mesangium cell proliferation-inhibiting action and capable of being effectively used as a therapeutic medicine for nephritis.

This preparation contains a hydroxamic acid derivative of the formula [R1 is an aryl, etc.,; L is an alkylene, etc., (n) is an integer of 0 or 1; R2 is H, an alkyl, etc.,; M is H, a medically acceptable cation, etc.], e.g. [N-hydroxy-N-(1-phenylethyl)-4-(3-(4-methoxyphenoxy) styryl)benzamide]. The hydroxamic acid derivative can be synthesized by a method described in a Japanese unexamined patent: Hei 7-278086, etc., and can remarkably depress the proliferation of cultured rat masangium cells.