Abstract: An expanded programmable memory controller (PMC) is provided outside a numerical control device and connected to a main body programmable machine controller (PMC) which is inside the numerical control apparatus. The expanded programmable machine controller has a first sequence program, a second sequence program and a switching control mechanism. The first sequence program controls equipment connected to the expanded PMC. The second sequence program pseudo-executes an operation performed by the main body PMC. The switching control mechanism performs switching operation when an I/O signal of the first sequence program is supplied to or received from the main body PMC and when the I/O signal of the first sequence program is supplied to or received from the second sequence program so that when supplied to or received from the second sequence program, the first sequence and the second sequence programs are alternatively executed.