The present invention relates to a water-soluble composition for removing rust from steel bars and steel frames, which is environmentally harmless and permits improving work efficiency by allowing work to be conducted in a state where rust was simply removed from the steel bars and frames by applying it on the steel bars or frames with a spray or brush. The rust-removing preparation of the present invention comprises a mixture of 10-11% by weight of phosphoric acid, 6-7% by weight of sodium pyrophosphate, 6-7% by weight of a hard water softener, 7-8% by weight of zeolite, 2-3% by weight of xanthan, 2-3% by weight of a surfactant, 4-5% by weight of stearic acid, 6-7% by weight of methyl alcohol and 2-3% by weight of a defoamer in 50-51% by weight of water.