[Problem] To provide: a decoding device that decodes and replays, at a suitable timing, sequentially transmitted information; a reception device; a transmission device; a transmission/reception system; a decoding method; and a storage medium having a decoding program stored therein. [Solution] A decoding unit 21 that decodes packets sent from a transmission device 10. A decoding timing determination unit 22 determines the timing that the decoding unit 21 decodes packets, on the basis of adjustment information that is included in the packet and corresponds to time adjustment for making Coordinated Universal Time approach Universal Time. A packet includes processing interval information indicating the processing interval for an access unit being a set including the packet. The decoding timing determination unit 22 determines that packets constituting each access unit will be sequentially decoded at an interval corresponding to the interval indicated by the processing interval information, if the adjustment information indicates that a time adjustment will occur.