Abstract: The present invention is directed to a lyophilized preparation which contains a synthetic quinolone antibacterial compound and, as a solo additive, a pH-adjusting agent, and which exhibits an excellent reconstituting property. The invention provides a method for producing a lyophilized preparation containing a synthetic quinolone antibacterial compound as an active ingredient, characterized by including, sequentially, cooling an aqueous solution containing a synthetic quinolone antibacterial compound and a pH-adjusting agent to yield a frozen product, elevating the temperature of the frozen product, and re-cooling the resultant to prepare the lyophilized preparation.