To provide a metal plate working system capable of performing suitable positioning free from the occurrence of imperfect positioning and surplus pushing in accordance with movement resistance upon the positioning different each time.

The metal plate working system is provided with: a metal plate working machine 1 such as a punch press; a metal plate loader 2; and a metal plate loader controller 3. The metal plate loader 2 includes: a metal plate holding means 4 for holding a metal plate W; and a moving mechanism 19 for moving the metal plate holding means 4 horizontally. The metal plate loader controller 3 includes: a load detecting means 42 for detecting a load when the metal plate W is held and is moved on a table 9 in the metal plate working machine 1; and an applying completion judging means 41, when the load detected by the load detecting means 42 reaches a threshold, judging that the metal plate W is applied to a positioning member 7. The threshold of the applying completion judging means 41 is determined by set rules 42a using the load detected by the load detecting means 42 by a threshold calculating means 40.