Provided are a wedge angle adjusting device and method. A device for adjusting a wedge angle of a variable wedge of an electro wedge brake (EWB) includes a movable wedge including an inclined surface and a counter wedge which includes an inclined surface disposed to face the inclined surface of the movable wedge and is disposed to face the movable wedge. The wedge angle adjusting device includes a frictional coefficient estimate unit configured to estimate a frictional coefficient between a pad and a disc of the EWB, a wedge angle command unit configured to calculate a wedge angle command value, based on a estimation of frictional coefficient estimated by the frictional coefficient estimate unit, and a wedge control unit configured to adjust the wedge angle according to the calculated wedge angle command value.