An operation history display system 1 creates, during a time set in advance, a graph G1 which is based on an operation history LG1 of a dental processing machine 100 and is stored in a storage 120 and in which a corresponding range to an operating time TM1 between a processing start time 133 and a processing end time 134 associated with each other is displayed in a first color CL1 and a corresponding range to a non-operating time TM2 that is not included in the operating time TM1 is displayed in a second color CL2, and displays the graph G1. A corresponding range to a non-operating time TM3 that is longer than the operating time TM1 of the processing program PG1 selected by the user is displayed in a third color CL3.
