A ventricular assist device includes a case, a pair of blood bags and a squeezing unit. The blood bags are installed inside the case. Each of the blood bags includes an inlet port connected to a ventricle of a heart to introduce therethrough blood flowing out from the ventricle, an internal space formed to store the blood introduced through the inlet port and an outlet port connected to an artery to discharge therethrough the blood stored in the internal space. The internal space has a variable volume. The squeezing unit is installed inside the case. The squeezing unit is configured to alternately squeeze the blood bags in such a way that, if one of the blood bags is squeezed to discharge the blood, the other blood bag is inflated to draw the blood.
