When the selective catalytic reduction reaction using ammonia as a reducing agent, relatively with denitration efficiency at low temperatures is good, provides a regeneration method of the catalyst oxidation of SO2 is not accompanied. A reproducing method of a denitration catalyst, while installing a spent denitration catalyst denitration apparatus, the denitration catalyst, by spraying pH7 more aqueous solutions, comprising the step of removing the surface of the denitration catalyst, the denitration catalyst there vanadium pentoxide least 43 wt%, BET specific surface area of ​​the denitration catalyst is a 30 m @ 2 / g or more, denitration catalyst after regeneration is regeneration method of the denitration catalyst used in the denitration at 200 ° C. or less.