A device for evaluating tire rolling resistance for a tire testing machine having a running drum, the device comprising: load rolls having surfaces that simulate a road surface on which a tire is to travel; a moving mechanism configured to move the load rolls alternately in an approaching direction in which the load rolls come closer to the tire and in a leaving direction in which the load rolls go away from the tire; a load sensor configured to detect a load acting on the tire in a state where the surface of the load rolls are in contact with the tire; a position sensor configured to detect a position of the load roll in a direction along the approaching direction and the leaving direction; a phase difference calculation unit configured to control the moving mechanism so that the load acting on the tire is varied and calculate a phase difference between a variation of the load and a variation of the position of the load roll on the basis of signals from the load sensor and the position sensor; and a rolling resistance evaluation unit configured to evaluate a rolling resistance of the tire as an evaluation target by comparing the phase difference calculated for the tire as the evaluation target by the phase difference calculation unit with a phase difference calculated for a reference tire by the phase difference calculation unit, characterized in that the load rolls are two or more load rolls (44A, 44B) disposed side by side and are smaller in diameter than the tire, the load rolls are disposed separately from a tire testing machine for testing the tire, and the load rolls are disposed separately from the running drum of the tire testing machine. load rolls having surfaces that simulate a road surface on which a tire is to travel; a moving mechanism configured to move the load rolls alternately in an approaching direction in which the load rolls come closer to the tire and in a leaving direction in which the load rolls go away from the tire; a load sensor configured to detect a load acting on the tire in a state where the surface of the load rolls are in contact with the tire; a position sensor configured to detect a position of the load roll in a direction along the approaching direction and the leaving direction; a phase difference calculation unit configured to control the moving mechanism so that the load acting on the tire is varied and calculate a phase difference between a variation of the load and a variation of the position of the load roll on the basis of signals from the load sensor and the position sensor; and a rolling resistance evaluation unit configured to evaluate a rolling resistance of the tire as an evaluation target by comparing the phase difference calculated for the tire as the evaluation target by the phase difference calculation unit with a phase difference calculated for a reference tire by the phase difference calculation unit, characterized in that the load rolls are two or more load rolls (44A, 44B) disposed side by side and are smaller in diameter than the tire, the load rolls are disposed separately from a tire testing machine for testing the tire, and the load rolls are disposed separately from the running drum of the tire testing machine.