Cardiac energetic efficiency is a ratio of cardiac workload to cardiac energy consumption, and cardiac workload is subject to vascular system. Although a number of computational circulation models have been developed, most of them represent the left ventricle as a time-varying elastance and so cannot compute cardiac energetic efficiency. In the present study, a cardiovascular dynamics model is introduced to assess cardiac energetic efficiency, by integrating a detailed ventricular cell model into a vasculature closed-loop circuit. The vasculature circuit is based on a vascular system model proposed by Heldt et al. (2004). Left ventricular pressure is converted, according to Laplace’s law, from the contractile force of ventricular myocyte which is calculated in a cell model by Kuzumoto et al. (2008). Despite combination of highly nonlinear sub-models, the present model successfully reproduce cardiac properties relating to energetic efficiency; response to variation of cardiac afterload, linearity of end-systolic pressure-volume relationship, and linear relationship between left ventricular oxygen consumption and pressure-volume area, which represents the total mechanical energy generated by ventricular contraction.