The invention relates to the technical field of bridge erecting construction equipment, in particular to a bridge erecting machine. The bridge erecting machine comprises a guiding beam, a front supporting leg, a middle supporting leg, a rear supporting leg and an auxiliary supporting leg, the front supporting leg, the middle supporting leg, the rear supporting leg and the auxiliary supporting leg are sequentially arranged on the guiding beam in the length direction of the guiding beam, a plurality of hoisting trolleys capable of moving in the length direction of the guiding beam are arranged at the top of the guiding beam, the top of the auxiliary supporting leg is hinged to the guiding beam, auxiliary supporting leg traveling wheels are arranged at the bottom of the auxiliary supporting leg, and a supporting crossbeam used for erecting the front end of a beam transporting vehicle is arranged on the auxiliary supporting leg. The bridge erecting machine is simple in structure and convenient to operate, the front end of the beam transporting vehicle is temporarily supported through the supporting crossbeam, thus a carrying trolley can be directly utilized to transport a box beam to the position below the bridge erecting machine, the box beam does not need to be transported through the beam transporting vehicle, thus the height of the bridge erecting machine in the whole process can be significantly decreased, and it is ensured that the demand for the height of a tunnel is met through the bridge erecting machine.