A power train support structure includes a first front side frame disposed on one of left and right sides of a power train; a second front side frame disposed on the other of the left and right sides of the power train, and being greatly away from the power train with respect to the first front side frame; a mounting bracket having one of left and right ends connected to the power train; and a connecting member for connecting the mounting bracket and the second front side frame. The mounting bracket includes a front fixing portion and a rear fixing portion to be fixed to the power train. A strength of the front fixing portion and the rear fixing portion is set to such a strength that the rear fixing portion is broken by a collision load from a front side, and the front fixing portion is not broken.