In an article from FredHarriman.com, ex-Toyota Group manager Chihiro Nakao relates his experience with Taiichi Ohno, who originated Toyota’s Lean Production in collaboration with Shigeo Shingo. Here’s the punchline:
As Mr. Taiichi Ohno drove deeper and deeper in the effort to achieve Just in Time ideals among the companies of the Toyota Group, […] the struggle was to keep people from [ordering] too much too soon from their upstream process.
In one incidence remembered by Chihiro Nakao, Mr. Ohno caught someone he knew was about to pull his materials too soon and thundered: “Who are you and where did you come from?! What makes you think you have any right to this material? Show me your kanban!!” [i.e. prove your authority!]
Such incidents demonstrated the need to “show one’s kanban” when procuring material or parts. They needed some way to prove that they had followed all the rules put in place to achieve Just in Time. Since Mr. Ohno’s demand for a “kanban” left a lasting impression, the name for the cards that were issued to limit in-process inventory […] became “kanban.”
Source: Toyota Stays Lean and Green with Kanban… Kan-who? / BNET, April 2nd, 2007