To provide a steel plate cooling device which is superior in cooling capacity and small in the variation of temperature distribution of a steel plate after the cooling.

In the cooling device to cool a steel plate 4 by spraying water jetted from a plurality of spray nozzles 3c arranged along the moving direction and the width direction of the steel plate 4, the maximum spread angle of the water jet is 10-30°, the distance from a tip of each spray nozzle to one surface of the steel plate is 200-700 mm, and the water amount density of the water jetted on one surface of the steel plate is ≥2 m3/m2/minute. The plurality of spray nozzles are arranged so that jetted collision areas of each water jetted on one surface are at least brought into contact with each other along the width direction of the steel plate and also at least brought into contact with each other along the inclining direction with respect to the width direction; and moreover, are arranged so that the jet collision areas arranged along the width direction overlap each other with the overlapping width in a range of ≥0% and ≤100% of the radius of each jet collision area. The heat transfer coefficient of the cooling device is ≥6,000 (W/m2×K).