A tire noise reduction device includes at least one noise absorbing member made of a porous material. The noise absorbing member is attached to the inner surface of the tire tread portion. The noise absorbing member includes multiple continuous grooves arranged side by side in a tire circumferential direction in the outer peripheral surface of the noise absorbing member. Each of the continuous grooves has an areal groove bottom and forms see-through regions in the width direction of the noise absorbing member. A groove edge-to-edge distance between each adjacent two of the continuous grooves in the tire circumferential direction is 2 mm to 40 mm. A largest see-through cross-sectional area of each continuous groove is 20 mm2 to 100 mm2.