Provided is a 1,3,4-oxadiazole-2-carboxamide compound which has STAT3 inhibitory activity and is useful as an anticancer agent. Provided is a 1,3,4-oxadiazole-2-carboxamide compound represented by formula (I) or a pharmacologically acceptable salt thereof (in the formula, Ar represents a furyl group or the like R 1 represents a hydrogen atom or the like and -X-Y represents a diaryl group such as a biphenyl group).STAT3 저해 활성을 갖고, 항암제로서 유용한 1,3,4-옥사디아졸-2-카르복사미드 화합물을 제공한다.식 (I) 로 나타내는 1,3,4-옥사디아졸-2-카르복사미드 화합물 또는 그들의 약리학적으로 허용되는 염 (식 중, Ar 은 푸릴기 등을, R1 은 수소 원자 등을, -X-Y 는 비페닐기 등의 디아릴기를 나타낸다).