PURPOSE: A cancer-targeting HSP90 alpha in a cancer cell exposed under a hypoxic condition is provided to regulate HSP90 alpha expression through JaK2/STAT5b in a tumor tissue.CONSTITUTION: A composition for diagnosing cancer contains HSP90 alpha as an active ingredient. Cancer is selected from the group consisting of breast cancer, prostate cancer, ovarian cancer, uterine cervix cancer, skin cancer, malignant melanoma, pancreatic cancer, colorectal cancer, kidney cancer, leukemia, non-small cell carcinoma, and lung cancer. A composition for diagnosing cancer contains a gene encoding HSP90 alpha as an active ingredient.COPYRIGHT KIPO 2013본 발명은 저산소 조건에 노출된 암세포에서 항암타깃 Hsp 90 알파의 용도에 관한 것이다.