A dilute sulfuric acid manufacturing apparatus 40 includes: a pipeline 42 or the like through which a raw material containing at least a sulfur component, a nitrogen component, and 40 to 80 wt.% or more of a water component are supplied; a PVSA 45d or the like that generates an oxygen-containing gas having an oxygen concentration of 22 to 40 vol.%; a combustion furnace 51 that combusts the raw material with the oxygen-containing gas to generate a combustion gas containing sulfur oxide (SOx: here, 1 ≤ x 3 ); and a dilute sulfuric acid tower 71 that cools the reaction gas to generate dilute sulfuric acid, in which less than 90 wt.% of the dilute sulfuric acid is generated only from the water component of the raw material without adding water from at least the combustion furnace 51 to the dilute sulfuric acid tower 71.