Information management method, identification information imparting apparatus, and information management system

An information management method comprising:

• spraying a visible liquid material on a part of a target object with an abnormal part to form a spray pattern comprising an irregularly-shaped outer periphery, wherein the spray pattern with an irregular shape of an outer periphery is formed by the visible liquid material being ejected and collided with the target object and scattered, or splashing after being ejected and before reaching the target object;
• storing a spray pattern image, which is obtained by photographing and imaging the spray pattern, and information about the target object in association with each other;
• and
• managing the information about the target object by using the irregular shape of the irregularly-shaped outer periphery of the spray pattern image as identification information of the target object.