1. A wireless communication apparatus which communicates with at least one wireless station apparatus by utilizing enhanced distributed channel access (EDCA) mechanism, comprising: a first channel state determining unit that determines a usage state of a communication channel which is used between the wireless communication apparatus and the wireless station apparatus in a contention period of the communication channel, in a situation where the wireless communication apparatus communicates with one wireless station apparatus; a first terminal occupation time calculating unit that calculates, on the basis of the usage state, a different-terminal occupation time in the contention period of the communication channel; a first traffic measuring unit that measures an amount of data received from the wireless station apparatus in the different-terminal occupation time; a first parameter adjusting unit that adjusts an EDCA parameter set used in the EDCA mechanism, on the basis of the different-terminal occupation time and the amount of data received from the wireless station apparatus; and a parameter updating unit that updates the EDCA parameter set to an adjusted EDCA parameter set.