We wonder what her kids think of all this!

Madonna recently joined Instagram, and the pop singer hasn't wasted any time uploading personal photos that show her in various states of undress! Even though she's in her 50's, Madge sees no problem with showing off her sexy bod, apparently!

In her latest post, the Grammy winner shows off her enviable backside in a picture taken backstage before one of her concerts. In another snapshot earlier this week, the mother-of-four showed off her cleavage dripping with sweat after a workout. Yikes!

Not all her updates are of a sexual nature, though!

The blonde bombshell also showed off a Valentine's Day card from one of her kids that read, "Happy Valentine's Day. You are the best and you make me so happy. I love you Mom."

When you are the Queen of Pop, you can do - and post - whatever you want!