The present invention relates to a fixation device for internally fixing fractures. The fixation device has an elongated support plate and a transverse plate and a fin member extending transversely from the elongated support plate. The elongated support plate and the transverse plate define a plurality of holes for receiving fixing elements to mount the fixation device onto a bone. The holes can be so located that the fixing elements can prevent the fixation device from rotating relatively to the bone after the fixation device is mounted onto the bone. Additionally, the fin member is formed to be more flexible than the transverse plate. Thereby, the fin member can be bent to conform to the contour of the bone for fixing or stabilizing a fractured fragment. As a result, the fixation device can both support the injured bone and fix/stabilize the fractured fragment.