A power conversion device capable of shortening the time required for acceleration of a motor and a metal processing device including the power conversion device are provided. Then, a power conversion device 10 includes a converter 100 configured to convert an AC voltage from outside to a DC voltage Vo and a converter controller 107 configured to control the converter 100. The converter 100 includes a voltage doubler circuit 104 configured to boost the DC voltage Vo when activated, and outputs the DC voltage Vo having a voltage value different in accordance with the activation and stop of the voltage doubler circuit 104. The converter controller 107 activates the voltage doubler circuit 104 at a first time that is earlier by a predetermined period than a second time at which a speed command value ω* of the motor 130 rises from a predetermined value.