A communication apparatus includes a plurality of first queues to which priorities or predetermined bandwidths are assigned respectively, a plurality of second queues which are corresponded to any of the plurality of first queues and to which the priorities are assigned respectively, a first writing portion which writes data blocks into any of the plurality of second queues or any of the plurality of first queues which is not corresponded to the second queues in accordance with a rule, a second writing portion which reads the data blocks stored in the plurality of second queues in order of the priorities assigned to the second queues respectively, and writes the data blocks into at least one of the first queues which is corresponded to the second queues, and a transmitting portion which reads the data blocks stored in the plurality of first queues in order of the priorities assigned to the first queues respectively or at time intervals corresponding to the bandwidths assigned to the first queues respectively, and transfers the data blocks to the communication network.