To provide a terminal apparatus, a program, and a communication bandwidth determination method which can correctly measure a communication bandwidth, without providing a server apparatus which measures the communication bandwidth.A controller of a measuring terminal apparatus fixes a measurement bit rate and, every time it increases a number of subject terminal apparatus, transmits measurement data to, or receives them from, the plurality of subject terminal apparatus at a fixed measurement bit rate, and measures the bit rate for each subject terminal apparatus. Then, the controller, in the event that a difference between a tallied bit rate before increasing the number of subject terminal apparatus and a tallied bit rate after increasing the number of subject terminal apparatus is less than or equal to a predetermined value, determines that the tallied bit rate at that time is the communication bandwidth of the measuring terminal apparatus.