A method of computing an energy loss generated in a viscoelastic material, including analyzing a dynamic behavior of a to-be-analyzed object composed of the viscoelastic material by a numerical analysis method; and computing the energy loss of the object momently when the object makes the dynamic behavior by a viscous component of the object. The energy loss computed by the energy loss computing method is visualized by a golf ball-hitting simulation to momently evaluate the energy loss generated in the golf ball.