Disclosed are a multi-pole circuit breaker and an apparatus for preventing deformation of a driving shaft thereof. The multi-pole circuit breaker includes: a plurality of single pole breaking units having a pair of fixed contactors, a movable contactor, and shafts; a switching mechanism disposed on a certain one of the plurality of single pole breaking units; a pair of driving shafts connected to each shaft; and a driving shaft deformation prevention unit disposed between the single pole breaking unit, spaced relatively far from the switching unit among the plurality of single pole breaking units, and the adjacent single pole breaking unit.