A machine learning device performs machine learning on a numerical control device which, when a first command including a corner portion, composed of two blocks in the machining program, generates a second command in which the two blocks are replaced with m or more blocks. The machine learning device comprises: a state information acquisition unit for acquiring state information including the first command, coordinate values of each block in the m or more blocks, and location information of the machining path and the machining time; an action information output unit for outputting action information; a reward output unit for outputting a reward value based on the inward turning amount in the corner portion; and a value function updating unit for updating a value function based on the value of the reward outputted from the reward output unit, the state information and the action information.