There are provided a communication apparatus, a generated data size controlling method, and a program for bringing a time required for a round-trip half-duplex communication close to a predetermined target time. A video data transmission section transmits data generated by a video data generation section to an HMD. A sensing data reception section receives data transmitted from the HMD. A required time identification section identifies the time required for the round-trip half-duplex communication between a repeating apparatus and the HMD. A generation control section controls a size of the data generated per unit time by the video data generation section on a basis of the identified time, the size of the data exchanged with the HMD in a round-trip communication, and a predetermined target time for the round-trip communication.