The present invention relates to a carbon material which contains boron atoms in an amount of 0.001-0.5 mass% and in which in analysis by X-ray diffractometry, the (002) planes have an average interplanar spacing (d002) of 0.337 nm or less. In an examination of the optical structures of a section of a molded object constituted of the carbon material, the carbon material has the relationships 1.5<=AROP<=6 and 0.2*D50<=(SOP*AROP)1/2<2*D50 where SOP is the area of an optical structure which is to be added at the time when the cumulative area calculated by cumulation from the minimum-area structure reaches 60% of the total area of all the optical structures, AROP is the aspect ratio of a structure which is placed at 60% of the number of all the structures when the structures are counted in ascending order of aspect ratio, and D50 is the average grain diameter. The invention further relates to a secondary battery wherein this carbon material is used as an electrode material.