1. An information processing apparatus with an instruction prefetch function, said apparatus being responsive to instruction signals and break signals from an external source, each said break signal corresponding to a respective instruction signal but being independent of the nature of the instruction signal or the result of an execution of the instruction signal, and comprising: an execution unit responsive to said instruction signals for executing at least one of several instructions at a time, an instruction prefetch unit for storing instruction signals and break signals, said unit being connected to said execution unit and having an instruction storage means for conducting instruction read-in and read-out operations for temporarily storing at least one of said several instruction signals and an indication storage means for storing at least one break signal designating a break operation that is to occur in relation to said stored instruction signals, said break signals stored in said indication storage means corresponds to respective instruction signals stored in said instruction storage means in a 1:1 relationship and said indication storage means operating to read-in and read-out break signals in synchronism with the read-in and read-out operations of said instruction storage means, read means coupled to said instruction storage means and said indication storage means for reading the content of said instruction storage means and the content of said indication storage means, and stopping means responsive to said read means for stopping an execution of the read-out instruction signals in said execution unit in response to the read-out break signal.