A high-strength pearlitic steel rail having excellent delayed fracture properties, characterized by having: a composition consisting of, in mass percent, C of 0.6% or more and 1.0% or less, Si of 0.1% or more and 1.2% or less, Mn of 0.4% or more and 2.0% or less, P of 0.035% or less, S of 0.0100% or less, Ca of 0.0010% or more and 0.010% or less and optionally of one or at least two selected from V of 0.5% or less, Cr of 1.5% or less, Cu of 1% or less, Ni of 1% or less, Nb of 0.05% or less, Mo of 1% or less, and W of 1% or less, and the remainder being Fe and inevitable impurities, wherein O is present in an amount of 0.002% or less in the composition, wherein hydrogen is present in an amount of 2ppm by mass or less in the composition, and wherein the upper limit value of N is 0.005%, and the upper limit value of each of Al and Ti is 0.0010 %, wherein tensile strength is 1200 MPa or more, and the maximum size of a long side of a C type inclusion is 50 μm or less in at least a cross-section in a longitudinal direction of a rail head, wherein the C type inclusions are observed in a view field of 50 mm 2 with a magnification of 500 by an optical microscope, each inclusion having a size of a long side of 0.5μm or more, and the number of C type inclusions, each having a size of a long side of 1 μm or more and 50 μm or less, is 0.2 or more and 10 or less per observed area of 1 mm 2 in the cross-section in the longitudinal direction of the rail head, wherein C type inclusions are those defined in Appendix 1 of JIS G0555, and wherein ACR defined by the following expression is 0.05 or more and 1.20 or less in the composition; ACR = 1 1.25 % Ca − 0.18 + 130 % Ca % O % S wherein ACR shows Atomic Concentration Ratio, [%Ca] shows Ca content (mass percent), [%O] shows O content (mass percent), and [%S] shows S content (mass percent). a composition consisting of, in mass percent, C of 0.6% or more and 1.0% or less, Si of 0.1% or more and 1.2% or less, Mn of 0.4% or more and 2.0% or less, P of 0.035% or less, S of 0.0100% or less, Ca of 0.0010% or more and 0.010% or less and optionally of one or at least two selected from V of 0.5% or less, Cr of 1.5% or less, Cu of 1% or less, Ni of 1% or less, Nb of 0.05% or less, Mo of 1% or less, and W of 1% or less, and the remainder being Fe and inevitable impurities, wherein O is present in an amount of 0.002% or less in the composition, wherein hydrogen is present in an amount of 2ppm by mass or less in the composition, and wherein the upper limit value of N is 0.005%, and the upper limit value of each of Al and Ti is 0.0010 %, wherein tensile strength is 1200 MPa or more, and the maximum size of a long side of a C type inclusion is 50 μm or less in at least a cross-section in a longitudinal direction of a rail head, wherein the C type inclusions are observed in a view field of 50 mm 2 with a magnification of 500 by an optical microscope, each inclusion having a size of a long side of 0.5μm or more, and the number of C type inclusions, each having a size of a long side of 1 μm or more and 50 μm or less, is 0.2 or more and 10 or less per observed area of 1 mm 2 in the cross-section in the longitudinal direction of the rail head, wherein C type inclusions are those defined in Appendix 1 of JIS G0555, and wherein ACR defined by the following expression is 0.05 or more and 1.20 or less in the composition; ACR = 1 1.25 % Ca − 0.18 + 130 % Ca % O % S ACR shows Atomic Concentration Ratio, [%Ca] shows Ca content (mass percent), [%O] shows O content (mass percent), and [%S] shows S content (mass percent).