Abstract: The present invention provides a novel method capable of producing hydrocomposites through the effective utilization of all of the components contained in iron and steel slag, while reducing the amount of slag waste. The invention also provides the hydrocomposites obtained by the method. The production method comprises: a mixture producing step by adding solid base to an iron and steel slag-containing starting material and mixing them to produce a mixture; a molten chips producing step by melting the mixture obtained in the mixture producing step at a temperature within the range of 100-1000° C. to produce molten chips; and a hydrocomposite producing step by adding the molten chips obtained in the molten chips producing step to a solvent to produce a solution and then producing a hydrocomposite from the solution.