An object of the invention is to provide an aqueous solution of a No. 1 permanent waving agent through reconstitution upon use in a simple manner, which solution contains a cyclic mercapto compound as a reducing agent and realizes excellent characteristics such as high waving effect and good appearance of waved hair. The invention provides an alkylene carbonate dilution containing a cyclic mercapto compound in an amount of 7 to 80 wt. % an alkylene carbonate for use in preparation of the alkylene carbonate dilution and an aqueous reducing chemical agent which is prepared from the alkylene carbonate dilution and an aqueous base material.
