Degreasing method and degreasing apparatus

摘要

Prior to immersion of an object to be treated in a degreasing liquid, an aqueous solution 20 having a pH of 5.5 to 10. 0 is put into a sac-shaped portion of a vehicle body 2. Even when the vehicle body 2 is passed through the degreasing liquid, the aqueous solution 20 is not replaced with the degreasing liquid, and alkaline solid substances do not remain in the hemmed portion 2a. This prevents the water in the sac-shaped portion from having the high alkalinity even when water comes into the hemmed portion 2a later. The degreasing method can prevent the decrease in corrosion resistance of the joint portion of the object to be treated.