PURPOSE: To improve the efficiency of an information processing system, by processing a skip file instruction having a comparatively long processing time in a high speed mode with no intervention of an upper device.

CONSTITUTION: An upper device 30 outputs a skip file instruction to a magnetic tape device MTC31, and the MTC31 outputs a skip file indicating signal to a magnetic tape device MTU32 by the skip file instruction. The MTU32 stores the speed that is not equal to the highest level under the present processing among plural processing speeds, then performs automatically a skip file action in the highest active mode of the MTU32. The active mode is reset automatically to the original one when a tape mark block is detected on a magnetic tape, and at the same time a skip file action end signal is sent to the MTC31. The MTC31 transfers an end signal to the device 30 to complete a skip file instruction. Thus the efficiency is improved for an information processing system, and the alteration of a user program can be eliminated.