I could use some help or advice!

I have a three year old boy that keeps on peeing on his bed room floor. I have asked him why he does it and all he says is that he had to go. I have tried to ground him to see if that would stop him from doing it it did not work. I have taken his toys and Cartoons from him. That did not work. I am out of options on what to do to stop him from doing this. If you have any ideas please let me know. Or if you might know why he does this that would help also.
Thank you,
Jennifer