A washing machine comprising: a main body configured to form an exterior of the washing machine and includes a laundry port formed in a front frame of the main body; a tub installed inside the main body and configured to accommodate water; a drum rotatably installed inside the tub and configured to accommodate laundry; a detector configured to detect a temperature inside the tub; a main door installed in the front frame of the main body to open or close the laundry port; an auxiliary door installed in the main door and configured to be openable or closable separately from the main door; a main locking device installed in the front frame of the main body; a main locking part installed in the main door and configured to be insertable into and detachable from the main locking device to maintain the main door in a closed and opened state, respectively; an auxiliary locking device installed in the main door; an auxiliary locking part installed in the auxiliary door and configured to be insertable into and detachable from the auxiliary locking device to maintain the auxiliary door in a closed or open state, respectively; characterised by further comprising: an inputter configured to receive an operational signal for opening or closing of the auxiliary door; and a controller configured, in response to the operational signal, to control a locking of the auxiliary door using the auxiliary locking device based on the temperature detected by the detector, wherein the controller is further configured to unlock the main door and the auxiliary door when it is determined that the cycle of the washing machine has finished. a main body configured to form an exterior of the washing machine and includes a laundry port formed in a front frame of the main body; a tub installed inside the main body and configured to accommodate water; a drum rotatably installed inside the tub and configured to accommodate laundry; a detector configured to detect a temperature inside the tub; a main door installed in the front frame of the main body to open or close the laundry port; an auxiliary door installed in the main door and configured to be openable or closable separately from the main door; a main locking device installed in the front frame of the main body; a main locking part installed in the main door and configured to be insertable into and detachable from the main locking device to maintain the main door in a closed and opened state, respectively; an auxiliary locking device installed in the main door; an auxiliary locking part installed in the auxiliary door and configured to be insertable into and detachable from the auxiliary locking device to maintain the auxiliary door in a closed or open state, respectively; an inputter configured to receive an operational signal for opening or closing of the auxiliary door; and a controller configured, in response to the operational signal, to control a locking of the auxiliary door using the auxiliary locking device based on the temperature detected by the detector, wherein the controller is further configured to unlock the main door and the auxiliary door when it is determined that the cycle of the washing machine has finished.