1. An instruction execution device that executes instructions stored in a storage device, comprising: a storage unit operable to store a value that is an instruction execution result; an execution unit operable to execute a debug instruction that interrupts instruction execution; an identification unit operable to identify, from a bit sequence that constitutes the debug instruction, a conditional expression that uses, as an operand, the value stored in the storage unit; and a judgment unit operable to judge whether or not the identified conditional expression is true or false, by referring to the value stored in the storage unit, wherein the execution unit suppresses execution of the debug instruction when the conditional expression is judged to be false.