A heavy-duty pneumatic tire having, in a tread surface, blocks (B 2) defined by a plurality of circumferential main grooves each continuously extending in a tire circumferential direction and a plurality of transverse grooves each communicating between circumferential main grooves adjacent in a tire width direction, wherein in a tire widthwise area that centers on a tire equator and whose width in the tire width direction is 50% of a tread width: at least one of the blocks (B 2) has a block partitioning groove that is open to each of transverse grooves defining the block and is shallower than the circumferential main grooves, to divide the block (B 2) into a plurality of small blocks (b 11, b 22); and at least one of the small blocks (b 11, b 22) has a block auxiliary groove that is open to the block partitioning groove at one end and open to a corresponding circumferential main groove or transverse groove at an other end and is shallower than the circumferential main grooves, characterised in that:the block partitioning groove extends while being inclined with respect to the tread circumferential direction with small bends halfway; and the block auxiliary groove has one bend in the tire circumferential direction, and having shoulder blocks (S 2) defined by a tread ground contact edge, a circumferential main groove nearest the tread ground contact edge, and a plurality of lug grooves each open to the tread ground contact edge and the circumferential main groove nearest the tread ground contact edge, characterized in that at least one of the shoulder blocks (S 2) has an auxiliary lateral groove which is formed so that the straight or curved line drawn continuously to represent the center of the opening of the auxiliary lateral groove to the tread surface in the groove extending direction is continuous with that of the block auxiliary groove in the small block (b 11, b 22) and is shallower than the circumferential main grooves. at least one of the blocks (B 2) has a block partitioning groove that is open to each of transverse grooves defining the block and is shallower than the circumferential main grooves, to divide the block (B 2) into a plurality of small blocks (b 11, b 22); and at least one of the small blocks (b 11, b 22) has a block auxiliary groove that is open to the block partitioning groove at one end and open to a corresponding circumferential main groove or transverse groove at an other end and is shallower than the circumferential main grooves, characterised in that:the block partitioning groove extends while being inclined with respect to the tread circumferential direction with small bends halfway; and the block auxiliary groove has one bend in the tire circumferential direction, and having shoulder blocks (S 2) defined by a tread ground contact edge, a circumferential main groove nearest the tread ground contact edge, and a plurality of lug grooves each open to the tread ground contact edge and the circumferential main groove nearest the tread ground contact edge, characterized in that at least one of the shoulder blocks (S 2) has an auxiliary lateral groove which is formed so that the straight or curved line drawn continuously to represent the center of the opening of the auxiliary lateral groove to the tread surface in the groove extending direction is continuous with that of the block auxiliary groove in the small block (b 11, b 22) and is shallower than the circumferential main grooves.