To provide a workpiece cooling device capable of quickly cooling a workpiece without causing variation of workpiece hardness and distortion after heat treatment.

This workpiece cooling device includes a cooling shelf 7 for placing the workpieces W after heat treatment, a robotic arm for individually conveying the workpieces W from the preceding process to the cooling shelf 7 to place the workpieces on the cooling shelf while separating from each other, and conveying the cooled workpieces W to a post-process, and a cooling time measuring means for measuring a lapse time from placing onto the cooling shelf 7 by each workpiece W, determining termination of cooling of the workpiece W after the lapse of a prescribed time, and informing the robotic arm of the same.