Mechanical properties of linear thermoplastic polyurethanes (TPUs) prepared by polyaddition reaction using a polycarbonate diol (PCD), 1,4-butanediol (a chain extender) and 4,4'-diphenylmethane diissocyanate were investigated. Chemical composition among these three components was kept constant. Primary attention was directed to how chain length of an alkylene group in the PCD affected the mechanical properties of the resultant TPU. To clarify this effect, the PCDs were synthesized using 1,6-hexanediol and 1,12-dodecanediol. In addition, the TPUs from copolycarbonate diols containing these two components were also produced, and then extensively examined and further compared to the ones from the corresponding blended PCDs. From a practical point of view, weatherability and solubility in a polar solvent were also evaluated.