Serum levels of the soluble urokinase-type plasminogen activator receptor (suPAR) reflect immune and inflammatory activation, and are shown to be associated with cardiovascular outcomes. We herein investigated the potential association between suPAR and left ventricular diastolic dysfunction among patients with preserved left ventricular ejection fraction (LVEF) and sinus rhythm. Among 291 patients who had sinus rhythm and an LVEF of ≥50% enrolled in the study, 26 (8.9%) were considered to have diastolic dysfunction. Patients with diastolic dysfunction had lower estimated glomerular filtration rate (eGFR), and higher systolic blood pressure (BPs), BNP, C-reactive protein, and suPAR than those without diastolic dysfunction. As compared with the first suPAR quartile, the fourth suPAR quartile was significantly associated with both diastolic dysfunction with an odds ratio of 8.95 [95% confidence interval (CI), 1.04–77.0, P < 0.05] after adjusting for sex, age, BPs log(eGFR), CRP, and diuretic use. On the other hand, receiver-operating characteristic curve (ROC) analysis showed that addition of log(suPAR) to the combination of age, sex, and log(eGFR), CRP, and diuretic use did not significantly improve the prediction of diastolic dysfunction. Among cardiac patients with preserved LVEF, serum suPAR was associated with diastolic dysfunction independent of confounding factors by logistic regression analysis. However, according to the ROC analysis, the utility of suPAR as a biomarker for diastolic dysfunction may be limited from a clinical point of view.