A thermal displacement correction training unit has a virtual machine tool, a virtual machine tool control unit and a virtual machine tool display unit. The virtual machine tool has a precision decline imitating unit for imitating the process precision decline caused by the heat during operation in the virtual machine tool unit, and a precision decline calculation unit for finding the amount of precision decline that represents the process precision decline in the process machine unit imitated by the process precision imitating unit. The virtual machine tool control unit has a precision correction unit for finding the correction amount by which the processing point is corrected in response to thermal displacement, and a correction amount adjustment unit for adjusting the correction amount found by the precision correction unit. The virtual machine tool display unit displays the amount of precision decline and the correction amount.