Disclosed are an apparatus for transmitting a frame and a method for controlling the transmission of a frame for strict synchronization. The frame transmission apparatus includes a cycle controller for providing information about a transmission block of the transmission cycle, a transmission multiplexer for multiplexing and outputting synchronous frames and asynchronous frames input thereto through the frame transmission apparatus in one transmission cycle, and a transmission controller for controlling the transmission multiplexer such that total sizes of the multiplexed synchronous frames and asynchronous frames do not exceed a size of one transmission cycle using information about the sizes of the synchronous frames, the sizes of the asynchronous frames, and the transmission block of the transmission cycle provided by the cycle controller.