A bus system and a method of deciding a data transmission path are provided. The bus system includes a plurality of functional blocks; a ring bus which transmits data in a single direction; an arbiter which generates a bus grant signal according to a predetermined algorithm in response to a bus request from one of the functional blocks; and a plurality of bus connectors each of which connects a corresponding functional block to the ring bus, transmits data from the corresponding functional block to the ring bus, and transmits data from the ring bus to the corresponding functional block. The method includes synthesizing and laying out a bus system, simulating a case where a short-cut bus is used when data is transmitted between functional blocks and a case where the short-cut bus is not used, and generating a bus selection table, to be referred to for selection of a bus, based on the simulation results.