A vehicle driving force distribution device, comprising: a differential gear that distributes a driving force received from an input shaft to a first output shaft and an intermediate shaft so as to allow differential motion therebetween; a driving force transmission device having a function to adjust the driving force that is transmitted from the intermediate shaft to a second output shaft; and a case member including a first accommodating chamber accommodating the differential gear, and a second accommodating chamber accommodating the driving force transmission device; wherein the case member has a first flow passage that allows lubricating oil to flow from the first accommodating chamber into the second accommodating chamber, and a second flow passage that allows lubricating oil to flow from the second accommodating chamber into the first accommodating chamber, the vehicle driving force distribution device is configured such that, when the input shaft does not rotate and the intermediate shaft and the second output shaft rotate in opposite directions, lubricating oil flows from the second accommodating chamber into the first accommodating chamber through the second flow passage, and the vehicle driving force distribution device is configured such that, when the input shaft rotates and the intermediate shaft and the second output shaft rotate in a same direction, lubricating oil flows from the first accommodating chamber into the second accommodating chamber through the first flow passage, characterized in that the case member has a third flow passage that allows lubricating oil to flow from the second accommodating chamber into the first accommodating chamber when the amount of lubricating oil in the second accommodating chamber becomes larger than a predetermined amount. a differential gear that distributes a driving force received from an input shaft to a first output shaft and an intermediate shaft so as to allow differential motion therebetween; a driving force transmission device having a function to adjust the driving force that is transmitted from the intermediate shaft to a second output shaft; and a case member including a first accommodating chamber accommodating the differential gear, and a second accommodating chamber accommodating the driving force transmission device; wherein the case member has a first flow passage that allows lubricating oil to flow from the first accommodating chamber into the second accommodating chamber, and a second flow passage that allows lubricating oil to flow from the second accommodating chamber into the first accommodating chamber, the vehicle driving force distribution device is configured such that, when the input shaft does not rotate and the intermediate shaft and the second output shaft rotate in opposite directions, lubricating oil flows from the second accommodating chamber into the first accommodating chamber through the second flow passage, and the vehicle driving force distribution device is configured such that, when the input shaft rotates and the intermediate shaft and the second output shaft rotate in a same direction, lubricating oil flows from the first accommodating chamber into the second accommodating chamber through the first flow passage, characterized in that the case member has a third flow passage that allows lubricating oil to flow from the second accommodating chamber into the first accommodating chamber when the amount of lubricating oil in the second accommodating chamber becomes larger than a predetermined amount.