An X-ray spectrometer for high-resolution Compton profile measurements using 90-120 keV X-rays has been designed and constructed at SPring-8. A Cauchois-type triply layered bent-crystal analyzer was employed for the energy analysis. A novel use of a solid-state detector with a large active area was devised as a position-sensitive detector. A resolution of 0.10 atomic units in electron momentum has been achieved at an incident X-ray energy of 115 keV. A Compton profile of a single crystal of Nb was measured with a counting rate of 30 counts s-1 at the Compton peak, which demonstrates that the spectrometer is capable of measuring Compton profiles of heavy-element materials.