A memory system, a memory device, a memory controller and an operating method thereof. By issuing a first status check signal when a first delay time elapses since a first point in time at which a program operation for first memory cells corresponding to a first word line is started and by issuing a second status check signal when a second delay time different from the first delay time elapses since a second point in time at which a program operation for second memory cells corresponding to a second word line is started, it is possible to efficiently perform a status check operation related with a program operation of data.