PURPOSE: To learn a neural network without loading on the numerical control by using a numerical controller different from the one which performs the machining control based on the accumulated input data and teacher data in order to learn the coupling coefficient of the neural network with use of an off-line method.
CONSTITUTION: A CPU 40 of a learning device inputs the learnt coupling coefficient data on the 1st and 2nd neural networks through a flexible disk FD 37 and stores the input coupling coefficient data in a coupling coefficient area 462 of a RAM 46. At the same time, the CPU 40 inputs and stores the teacher data in a teacher data area 463. Furthermore, the CPU 40 inputs the input data through the FD 37 to store it in an input data area 464 and also stores an arithmetic program in a neural network area 461. A numerical controller 30 learns a coupling coefficient by means of the high speed computing ability of an off-line learning device based on the accumulated teacher data in an actual application state.As a result, the precise learning of the neural networks can be attained without loading on the machining control of the controller 30.