Electrophotographic toner, electrophotographic developer and image formation method using the same

An image formation method comprising forming at least one invisible image selected from invisible images formed when (a) forming only an invisible image on the surface of an image output medium, (b) forming an invisible image and a visible image by laminating these images one by one on the surface of the image output medium and (c) forming an invisible image and a visible image separately in different regions on the surface of the image output medium, wherein at least one of the invisible images of (a), (b) and (c) is composed of a two-dimensional pattern, wherein

• the invisible image is formed using an electrophotographic toner comprising:
• at least a binder resin and a near-infrared light absorbing material consisting of inorganic material particles,
• wherein the rate of absorption in the visible region of the electrophotographic toner is 15% or less and the average dispersion diameter of the near-infrared light absorbing material is in a range from 50 nm to 800 nm,
• and wherein the inorganic material particles are glass obtained by adding at least a transition metal ion.