An activated carbon having a high catalytic activity as an oxidation catalyst or a decomposition catalyst, and use therefor are provided.The activated carbon has (a) an oxygen content in a range from 1.40 to 4.30% by mass, (b) a nitrogen content in a range from 0.90 to 2.30% by mass, (c) a sulfur content in a range from 0.50 to 1.20% by mass, and (d) a hydrogen content in a range from 0.40 to 0.65% by mass. The activated carbon may have at least one characteristic of (e) an amount of an acidic surface functional group of 0.10 to 0.36 meq/g, (f) an amount of a basic surface functional group of 0.50 to 1.30 meq/g, and (g) a benzene adsorption capacity of 25 to 50%. The activated carbon catalyzes an oxidation reaction of N-(phosphonomethyl)iminodiacetic acid with a peroxide (e.g., hydrogen peroxide) and achieves an efficient production of N-(phosphonomethyl)glycine even after repetitive use. The activated carbon also efficiently decomposes a chloramine.