A forming speed determination method for determining a forming speed of a press-processing device with a plurality of measurement points on a sheet material to conduct press-forming of the sheet material with a press-processing device at a predetermined forming speed. Strain states at respective points on the press-formed sheet material are plotted on a forming limit diagram including the forming limit curve of a sheet material to produce a strain distribution chart. Subsequently, the closest point to the forming limit curve among the points is defined as a specific measurement point. When this specific measurement point is located in the bulge region, the forming speed of a press-processing device is decreased to be slower than the above-mentioned predetermined forming speed. Meanwhile, when this specific measurement point is located in the draw region, the forming speed of a press-processing device is increased to be faster than the above-mentioned predetermined forming speed.