[Problem] The present invention provides a 4,6-diaminonicotinamide compound which is useful as an active ingredient of a pharmaceutical composition, in particular, a pharmaceutical composition for treating diseases caused by undesirable and/or abnormal cytokine signal transduction. [Means for Solution] The present inventors have extensively studied compounds having a JAK3 inhibitory action, and as a result, they have found that a 4,6-diaminonicotinamide compound which is the compound of the present invention has an excellent JAK3 inhibitory action and is useful as an agent for preventing or treating diseases caused by undesirable and/or abnormal cytokine signal transduction, thereby completing the present invention.
