Recently the treatment strategy of Philadelphia chromosome-positive leukemia has undergone groundbreaking changes due to the development of new second-generation cancer-targeting drugs. After 2001, a seven-year survival for leukemia stands at as much as 86 percent due to the oral therapy of cancer-targeting imatinib as a standard treatment, but drug resistance occurs in some patients in the early stage of the treatment. It is known that weakened binding ability of imatinib to BCR-ABL is due to a point mutation in the ATP-binding site of BCR-ABL. This accounts for 70 percent of causes of imatinib resistance. According to the studies so far, there are approximately more than 60 types of BCR-ABL point mutation, which causes imatinib resistance.