To compare inversion time (TI) parameters, native T1, and extracellular volume (ECV) on cardiac magnetic resonance (CMR) imaging between patients with cardiac amyloidosis (CA) or hypertrophic cardiomyopathy (HCMP). Forty six patients with biopsy-confirmed CA and 30 patients with HCMP who underwent CMR were included. T1 and TI values were measured in the septum and cavity of the left ventricle on T1 mapping and TI scout images. TI values were selected at nulling point for each myocardium and blood pool. Native T1, ECV, and TI interval values were significantly different between the CA (1170.5 ± 86.4 ms, 56.7 ± 12.2, - 11.5 ± 28.4 ms) and HCMP (1059.5 ± 63.4 ms, 28.5 ± 5.8, 66.2 ± 25.4 ms) (all p < 0.001). The diagnostic performance of the TI interval (area under the ROC curve, 0.975) was not inferior to that of the ECV (0.980, p = 0.776), and it was superior to that of the native T1 (0.845, p = 0.004). The diagnostic performance of TI interval was comparable to that of ECV for differential diagnosis between CA and HCMP. TI interval showed the feasibility as quantitative CMR parameter when T1 mapping images are not available.