We theoretically investigated the resolution of the photonic crystal (PC) K-vector superprism, which utilized the wavelength-dependent refraction of light at an angled output end as a narrow band filter at 1.55 µm wavelength range. Similarly to the case of the conventional S-vector prism, we defined the equi-incident-angle curve against the dispersion surface, and calculated the beam collimation, wavelength sensitivity and resolution parameters for light propagation in the PC. We estimated that the resolution of the K-vector prism is the same as or higher than that of the S-vector prism and the PC can be significantly miniaturized. In addition, we clarified the relation of the S-vector prism phenomenon and the position of the output end in the K-vector prism, and different results for the reduced and repeated zone schemes, which are important for the detailed design. We also confirmed that the light propagation simulated by the FDTD method well agreed with the results of the dispersion surface analysis.