The invention provides a bit breaker comprising a generally flat plate that defines two arms and a base leg. The two arms project respectively from opposed ends of the base leg. The bit breaker has a generally rectangular pipe slot located between the two arms. The bit breaker includes a jaw mounted on one of the arms so as to be removable therefrom when damaged and thereafter replaced with a new jaw. The jaw defines a working surface located on a side of the pipe slot. In some embodiments, the bit breaker further comprises a security plate attached to the generally flat plate so as to define a mount space between the generally flat plate and the security plate. The jaw is received in the mount space such that the jaw has limited freedom of movement relative to both the generally flat plate and the security plate.