To provide a hot dip metal plating apparatus which can deal with the width change of a steel sheet, and is low in initial cost and maintenance cost.

In the hot dip metal plating apparatus, a steel sheet 13 is dipped via a sink roll 12 provided at a plating tank 11 of hot dip metal, to the steel sheet 13 taken out from the plating tank 11 to a prescribed direction, the amount of plating stuck to the steel sheet 13 is uniformly controlled with air or nitrogen from wiping nozzles 14, 15, and further, three or more gas sensors 27 to 29 detecting the warpage of the steel sheet 13 taken out from the plating tank 11 are provided. Two among gas sensors 27 to 29 are arranged on both the sides of the steel sheet 13, further, the gap sensors 27, 28 arranged on both the sides are controllably fitted to the width direction of the steel sheet 13, and the warpage of the steel sheet 13 is detected from data measured by the gap sensors 27 to 29.