A spectral resolution measurement of the x-ray imaging crystal spectrometer for the Korea Superconducting Tokamak Advanced Research machine utilizing a segmented position-sensitive detector and time-to-digital converter based delay-line readout electronics was performed by using an x-ray tube in a laboratory. The measured spectral resolution is about 12,600, which means the actual energy resolution is 0.32 eV for the x-ray tube's bremsstrahlung peak energy of 4 keV. The results from the spectral resolution measurement are described.