The present invention relates to the treatment of hand eczema. The problem to be solved by the invention is to provide a new pharmaceutical use of 3-[(3S,4R)-3-methyl-6-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1,6-diazaspiro[3,4]octan-1-yl]-3-oxopropanenitrile. A therapeutic or preventive agent for hand eczema, containing 3-[(3S,4R)-3-methyl-6-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1,6-diazaspiro[3,4]octan-1-yl]-3-oxopropanenitrile as an active ingredient.本發明係關於手部溼疹之治療。本發明欲解決之問題係提供3-[(3S,4R)-3-甲基-6-(7H-吡咯并[2,3-d]嘧啶-4-基)-1,6-二氮螺[3,4]辛-1-基]-3-側氧基丙腈之新穎醫藥用途。一種用於手部溼疹之治療性或預防性藥劑,其含有3-[(3S,4R)-3-甲基-6-(7H-吡咯并[2,3-d]嘧啶-4-基)-1,6-二氮螺[3,4]辛-1-基]-3-側氧基丙腈作為活性成分。