PURPOSE: To increase working efficiency and to improve the safety of working by mechanizing the bending work of a steel sheet.

CONSTITUTION: Many supporting pillars 3 the height of which is adjustable are arranged at proper intervals and a contact-detector sensor 22 for detecting that the steel sheet 2 is brought into contact with a supporting part 21 is provided on each supporting pillar 3. By elevating the main body 4 of the supporting pillar by a certain amount, moving a heat source part 14 and cooling part 15 above noncontact places (supporting pillars 3) where the contact-detector sensors 22 are in the off-state and repeating heating and rapid cooling till the contact-detector sensors 22 are turned on, the steel sheet is bent. When bending of one noncontact place is completed, the steel sheet 2 is bent by moving the heating part and cooling part to other noncontact places after completing one non-contact place. In such a way, when all contact-detector sensors 22 are turned on, by elevating the supporting pillar 3 again by a certain amount and repeating heating and cooling, the steel sheet 2 is bent. Like this, the rising of the supporting pillar 3 and bending work by heating and cooling are repeated till a desired shape is obtained.