A first object of the present invention is to provide Co-based alloys for biomedical applications which are Ni-free, high intensity and high elastic modulus and are suitable for plastic workability. Moreover, a second object of the present invention is to provide Co-based alloys for biomedical applications having X-ray visibility. Furthermore, a third object of the present invention is to provide a stent using the alloys. The Co-based alloys for biomedical applications according to the present invention is configured by adding alloy elements having biocompatibility and an effect of increasing stacking fault energy of the alloys.