This detergent composition for a steel plate contains an inorganic alkaline agent (component A), at least one type of organic acid selected from the group consisting of gluconic acid and ethylenediaminetetraacetic acid or a salt thereof (component (B), a nonionic surfactant represented by formula (1) (component C), an alkyl glucoside represented by formula (2) (component D), a fatty acid represented by formula (3) or a salt thereof (component E), and water (component F), the content of component A being 25% by mass to 34% by mass, the content of component D being 0.3% by mass to 2.9% by mass, and the content of component F being 57% by mass to 74% by mass. Through the present invention, it is possible to provide a detergent composition for a steel plate which can be stably stored at a high concentration while maintaining good cleaning ability at low temperature, a cleaning method using the detergent composition, and a steel plate manufacturing method including the aforementioned cleaning method in a manufacturing step thereof. (1): R1-O-[(EO)n/(PO)m]-H. (2): R2-Gx. (3): R3-COOM.