Do graphic designers need to have the ability to draw?

It's not really mandatory however you need to be good at sketching your ideas to get a rough picture before you start executing. Drawing is an added value skill as a designer. 

I think its mandatory, not only because designers need to do sketches while cnforming ideas, but good designs comes from those who can draw because they have richer imagination, and easier ability to turn their imaginations into clear designs, while designers with no artistic background usually fail to illustrate an idea that is clear and visible to everybody.

designer must drawing any thing even he not good or professional in drawing 

It would be an advantage but I don't think it is mandatory, because I have seen really good graphic design work by people who have said they can't really draw on paper. Like the other people here have said, its more about being able to think creatively, than the medium. Thanks for inviting expertise, Ola Qtaishat!

Yes! Sketching is very important especially in the first stage of the designing process. I call this the crucial stage because in this stage I and my client must both agree on what the outcome of the design. This will save me time and headache.

But before you start sketching you must have first the understanding what your client want, in short, you need to research first.

yes definately without drawing designing is not possible though 

Yes and not.I'm experienced illustrator also and I'm sure that you don't need to draw well, but, you must think well,that's much more important.As Mr. Perera is saying (the previous post), you must be able to think

well i don't think so, that it necessary to draw, some times you get ideas while you are drawing something, but actually mind creates ideas your job is to implement them on paper or on soft wares, it is about creativity, not about medium you are using,

If you can also draw, then it's a bonus to your skills, cause you never know what your next project would be. But of course, drawing skill is not a mandatory skill that a Graphic Designer should have.

Thank you for the invitation

The designer does not need to be able to draw, but must be familiar with the use of computing, the Internet and photography so that the design can work on the design

Not necessarily, because in my opinion it is ability to think