PURPOSE: To provide a program update managing system capable of updating one program from plural terminals simultaneously and an update managing method in a program update system.

CONSTITUTION: The programs for which a readout request is issued from the terminals 10, 20 are read out from a program library 50, and they are stored in a temporary storage part 41 transiently. After that, when the update requests of the program are issued from the terminals 10, 20, an update history acquiring means 32 compares the program for which the update request is issued with the program before update stored transiently, and acquires the update history of the program. It is judged whether or not the update part of an acquired update history is stored in an update history storage part 43 as the update history, and it is judged that the update of the program is valid when no update history is stored, and also, a program update means 33 rewrites the update part of the program stored transiently.