A pneumatic tire comprising, in a tread surface: at least two circumferential main grooves continuously extending in a tire circumferential direction; and at least one rib-like land portion each defined by two circumferential main grooves adjacent to each other from among the at least two circumferential main grooves, the rib-like land portion being a land portion in which no groove cuts across the land portion and has both ends open to the circumferential main grooves defining the land portion, and wherein the rib-like land portion has: a circumferential sipe including a circumferential sipe portion, being the portion of the circumferential sipe extending at an inclination angle of 20° or less with respect to the tire circumferential direction; and a both-end closed sipe having both ends terminating within the rib-like land portion, when a land portion width of the rib-like land portion is evenly divided by three where a region at a center in a tire width direction is a center region and regions on both sides of the center region in the tire width direction are side regions, the circumferential sipe portion is located only in the center region, the both-end closed sipe is located in any of the side regions and the both-end closed sipe is located only in the respective side region, wherein the radiuses of curvature (R4, R5) of the outer contour of the rib-like land portion decrease from the tire widthwise center side to the tire widthwise end side of the rib-like land portion, and the circumferential sipe comprises the circumferential sipe portion extending at an inclination angle of 20° or less with respect to the tire circumferential direction and located only in the center region and a widthwise sipe portion extending from the circumferential sipe portion in the tire width direction with an inclination angle equal to or less than 60°, and opening to a circumferential main groove which defines the rib-like land portion; characterized in that the circumferential main grooves extend linearly in the tire circumferential direction. at least two circumferential main grooves continuously extending in a tire circumferential direction; and at least one rib-like land portion each defined by two circumferential main grooves adjacent to each other from among the at least two circumferential main grooves, the rib-like land portion being a land portion in which no groove cuts across the land portion and has both ends open to the circumferential main grooves defining the land portion, and wherein the rib-like land portion has: a circumferential sipe including a circumferential sipe portion, being the portion of the circumferential sipe extending at an inclination angle of 20° or less with respect to the tire circumferential direction; and a both-end closed sipe having both ends terminating within the rib-like land portion, when a land portion width of the rib-like land portion is evenly divided by three where a region at a center in a tire width direction is a center region and regions on both sides of the center region in the tire width direction are side regions, the circumferential sipe portion is located only in the center region, the both-end closed sipe is located in any of the side regions and the both-end closed sipe is located only in the respective side region, wherein the radiuses of curvature (R4, R5) of the outer contour of the rib-like land portion decrease from the tire widthwise center side to the tire widthwise end side of the rib-like land portion, and the circumferential sipe comprises the circumferential sipe portion extending at an inclination angle of 20° or less with respect to the tire circumferential direction and located only in the center region and a widthwise sipe portion extending from the circumferential sipe portion in the tire width direction with an inclination angle equal to or less than 60°, and opening to a circumferential main groove which defines the rib-like land portion; characterized in that the circumferential main grooves extend linearly in the tire circumferential direction.