Provided is an electrode material which leads to a lithium ion secondary battery that has high energy density. An electrode material for a lithium ion secondary battery of the present invention is characterized by containing: a coarse particle of a first active material that is able to act as a positive electrode active material or a negative electrode active material of a lithium ion secondary battery; and a particle of a composite composed of conductive carbon and a second active material attached to the conductive carbon that is able to act as an active material of the same electrode as the first active material. This electrode material for a lithium ion secondary battery is also characterized in that: a diameter of the coarse particle of the first active material is larger than a diameter of the particle of the composite; and the particle of the composite is filled in a gap formed between the particles of the first active material. A conductive agent can be additionally contained in the gap.