The purpose of the present invention is to provide a therapeutic agent or prophylactic agent for pulmonary hypertension to treat pulmonary hypertension on the basis of a dual mechanism of action consisting of a pulmonary vasodilating action and an sEH inhibiting action, and to provide a therapeutic agent or prophylactic agent for pulmonary hypertension to be used in conjunction with a pulmonary vasodilator. The present invention provides a therapeutic agent or prophylactic agent for pulmonary hypertension containing, as active ingredients, a nipecotic acid derivative shown by the formula or a pharmaceutically acceptable salt thereof, and a pulmonary vasodilator.本發明之目的係提供基於肺血管擴張作用及sEH抑制作用兩者之作用機制而治療肺性高血壓的肺性高血壓之治療劑或預防劑,以及提供與肺血管擴張藥併用而使用的肺性高血壓之治療劑或預防劑。本發明係提供含有下式所代表的六氫菸鹼酸衍生物或其藥理學上可容許的鹽、及肺血管擴張藥作為有效成分的肺性高血壓之治療劑或預防劑。