The purpose of the present invention is to provide a compound having an excellent CDK4/6 inhibiting activity. The present invention is a compound represented by general formula (I) or a pharmaceutically acceptable salt thereof.本發明之目的為提供具有優良CDK4/6阻礙活性之化合物者。本發明為一般式(I)所示化合物或其醫藥上可被許可的鹽。