N-Terminal proB-type natriuretic peptide (NT-proBNP) is expected as a cardiac biomarker. However, it is unknown that the diagnostic accuracy of a point-of-care NT-proBNP ELISA kit in cats with heart diseases. In this study, we examined the diagnostic accuracy of the NT-proBNP test kit in cats with cardiac diseases and the relationship between this assay and blood NT-proBNP concentration. This study was enrolled 74 cats visiting from September 2017 until January 2019. Cats were divided into three groups; non-heart disease (non-HD; 41 cats), asymptomatic (22 cats), and heart failure (HF; 11 cats). Feline NT-proBNP ELISA kit was visually assessed as either positive or negative and blood concentration was measured using a commercial laboratory. Blood NT-proBNP concentrations in the asymptomatic and HF groups were significantly higher than those in the non-HD group. The test kit showed negative in all non-HD cats and in 6 of the asymptomatic cats, but positive in all HF cats. As a result, sensitivity and specificity for detecting cats with HDs were 81.8 and 100%, respectively (AUC = 0.91). The diagnostic accuracy of HDs was comparable between both methods. The NT-proBNP ELISA kit was able to detect cats with HDs with high accuracy. Although this kit can be useful as an additional method for detecting the HDs, echocardiographic examination is essential for final diagnosis. Further, it should be noted that negative results cannot completely exclude the HDs.