Optical transmission device including a bit rate adjustment function

A bit rate adjustment method executed by an optical transmission device for transmitting a first frame containing a plurality of second frames, comprising:

• newly adding and allocating, when a bit rate of a specific second frame among the plurality of second frames is to be changed, a time slot corresponding to an increase in the bit rate of the specific second frame to time slots previously set for the plurality of second frames in time slots of the first frame;
• inputting a dummy signal as data to the newly-added time slot while performing such a setting that both of:
• a data writing speed and a data reading speed for the newly-added time slot;
• and a delay time between writing and reading of the data for the newly-added time slot are in agreement with both of:
• a data writing speed and a data reading speed for each time slot of the previously-set time slots;
• and a delay time between writing and reading of the data for each time slot of the previously-set time slots;
• and
• causing the newly-added time slot and the previously-set time slots to contain the plurality of second frames so that the bit rate of the specific second frame is set to a bit rate defined in advance after the agreement.