A prediction method according to the present invention is a method for predicting a modal damping ratio of a composite head including two or more kinds of materials including a first material and a second material. The method includes the steps of: presuming at least a coefficient Px of a generalized Maxwell model M1 in the first material using a known material damping ratio ζ1; obtaining a calculation model of the head using the generalized Maxwell model M1; and calculating the modal damping ratio of the head based on analysis of the head using the calculation model. Preferably, the Maxwell model is further used also for the second material. Preferably, the method further includes the step of presuming a coefficient Py of a generalized Maxwell model M2 in the second material using a known material damping ratio ζ2.