PROBLEM TO BE SOLVED: To provide a heart supporter capable of stabilizing a cardiac output with respect to a circadian variation in an amount of circulating blood by improving ventricular work efficiency.SOLUTION: The design method of the heart supporter includes the steps of: determining a target value of a left ventricular end-diastolic pressure of the hear when wearing the heart supporter to be not less than a first left ventricular end-diastolic pressure and not more than a second left ventricular end-diastolic pressure that is more than the first left ventricular end-diastolic pressure； determining a first compression to the heart in the first left ventricular end-diastolic pressure, and a second compression to the heart in the second left ventricular end-diastolic pressure； and determining a physical property of the heart supporter on the basis of the first compression and the second compression.SELECTED DRAWING: Figure 8
