A transmitting apparatus accurately estimates an available bandwidth even in a high bandwidth in a network. The transmitting apparatus includes a timer that generates a signal having a signal cycle of a predetermined unit time and a packet train generating unit that generates probe packets each transmitted at the signal cycle, and generates, at least one adjustment packet inserted between two of the probe packets, the number of which corresponds to a measurement The apparatus also includes a transmitting unit that transmits, at the signal cycle, each probe packet having transmission time information, and the adjustment packet between the two probe packets, a receiving unit which receives, from a receiving apparatus, return information obtainable based on a reception time of each probe packet and a determining unit that determines the available bandwidth, using the received return information.