A transmission method for transmitting a lower-speed signal transmission frame using a node device in a network by accommodating the lower-speed signal transmission frame into time slots of a higher-speed signal transmission frame includes supplying, when a number of the time slots accommodating the lower-speed signal transmission frame is to be increased, the time slots to input numbers of a cross-connection part of the node device in accordance with an order of time slot numbers of the time slots; and re-establishing cross-connections where the input numbers are cross-connected to corresponding output numbers of the cross-connection part so that the cross-connections are prevented from crossing each other, wherein the input numbers input the time slots and the output numbers output the time slots.