Casey Anthony's Lawyer -- Bring On the Investigation!

Casey Anthony's attorney, Jose Baez, isn't concerned ONE BIT that the Florida State Bar has decided to investigate him over ethics concerns -- telling TMZ, he's used to being put through the wringer.

Jose tells us, he's "looking forward to the bar completing its investigation, so that it can be dismissed just like the 20 previous complaints."

Jose adds, "It is part of the job whenever you fight an unpopular cause."

As we previously reported -- Jose is being investigated for allegedly hiding information from the court ... after a clerical error gave Casey an unintentional break in her probation.