I have some termite damage ( I think ) . it goes into wall, how serious this damage looks like ? need major repair such as removing roof ? I have 4,5 looks like this.
thanks for your opinion.

 

First call a professional exterminator. You need to kill/stop the pests (termites, carpenter ants...) immediately. Termites do not start in the tail end of rafters, they had to go through the other parts of the house first before ever getting to the rafters. The eave and outer surface of the rafter appear good so I assume you don't have a water problem but if the damage is that extensive at the end of the rafter I would take a serious look at the rest of the rafters, ceiling joists, wall studs... Basically all the wood in the house.

As a quick check you can crawl under the house (if possible) and go up into the attic with a screw driver or sturdy ice pick and go around jabbing it into the wood. Very soon you will learn the difference between good solid wood and wood that is decayed or eaten. The screw driver will make a dent in good wood but not penetrate very deep. Rotten or eaten wood will have a hollow soft sound and the screw driver will penetrate much more deeply and often you can easily jab off chunks of wood. Also,when in the attic it's a good idea to check the ceiling joists in front of you before you put your weight on them. You don't want to put your weight on seriously damaged joists.