Method of analyzing interaction between material and biological substance

It is intended to provide a method of analyzing an interaction between a medical material and a biological substance. This method comprises bringing particles having a material to be evaluated at least on the surface thereof into contact with a biological substance to thereby form composite particles, bonding the biological substance directly or indirectly to a fluorescent label, and then measuring the fluorescent strength of the bounded matter with a flow cytometer to thereby analyze the interaction between the material and the biological substance. Based on the extent of this interaction, it can be judged whether or not the material is usable as a medical material for artificial vessels and so on.