Video Game Addicted, Is it Mental Disorder?

I've been wondering about it now. Can you call the video games addiction as a mental disorder? Maybe it's my mistake to buy the video game for my son. He is now playing with the games most of the time. If I see that happen, of course I will ask him to stop and take the game away. But sometimes, I am too busy to check it and he is playing just too long during the day.

I read somewhere online about this kind of addiction. Some people said that it is a kind of mental disorder as well. I don't know if it's true that you can categorize this kind of addiction into a mental disorder. But I just need to watch more careful about my son. I think I should try to search more information about this.