1. An optical disk apparatus comprising: a data conversion unit that converts input video data into record data; a data record unit that temporarily stores the record data provided by the data conversion unit in buffer memory and writes the record data stored in the buffer memory on to an optical disk while maintaining data continuity; and a control unit that controls the data record unit and the data conversion unit, wherein the control unit acquires free space of the buffer memory in a reference data unit smaller than a video object unit when the data conversion unit converts the video data into record data in the video object unit, the control unit instructs the data record unit to perform processing of dividing the record data in the video object unit into the reference data units and of storing in the buffer memory based on calculation data of the acquired free space of the buffer memory, the control unit instructs the data conversion unit to perform processing of converting the video data into record data when the record data in the video object unit is stored in the buffer memory, and the control unit instructs the data record unit to perform processing of dividing termination processing data made up of data in the last video object unit, end code data, and padding data into the reference data units and of storing in the buffer memory when a record stop instruction is input.