To replace a component feed unit accurately and quickly while enhancing productivity of board by designating removal of a comonent feed unit at next board regardless of a current board and designating a position to be processed.

The machine kind switching assisting system 1 comprises an information processor which can communicate bilaterally with a component mounter 2 through a transmission means. The electronic component mounter 2 recognizes the location of a component feed unit containing some type of component based on an arrangement data and mounts the component on a board according to a mounting program stored at a memory section 6. The machine kind switching assisting system 1 comprises a current board arrangement data memory section 8, a next board arrangement data memory section 9, and a comparison means 10 for generating and storing removing component information 12, transferring component information 13, and mounting component information 14. The system 1 further comprises means 15 for preparing a rearrangement guidance from the information 12-14 and includes information 16 of component setting direction, and the like.