The problems to be solved by the present invention are to provide a novel FGFR inhibitor that is potent and highly selective, and to provide an antitumor agent with which side effects such as an elevated blood phosphorus concentration are alleviated while maintaining the antitumor effect of the FGFR inhibitor. The present invention provides an antitumor agent comprising a 3,5-di-substituted benzene alkynyl compound represented by general formula (I) or salt thereof, which is used by administering the 3,5-di-substituted benzene alkynyl compound or salt thereof according to an administration schedule of two or more times/week at an administration interval of at least one day between doses.本發明所欲解決之課題係提供一種強力且高選擇性的新穎FGFR抑制劑，以及提供一種可一邊維持該FGFR抑制劑之抗腫瘤效果，且同時可減輕體重減少、血中磷濃度上昇等副作用之抗腫瘤劑。本發明係提供一種包含通式(I)所表示的3,5-二取代苯炔基化合物或其鹽之抗腫瘤劑，且其係以1週內2次以上且空出1日以上投予間隔的投予時程來投予的方式來使用該3,5-二取代苯炔基化合物或其鹽者。□
