To provide a base station device capable of estimating an arrival direction of a signal based on a receiving signal to decide an antenna pattern preferably.

A base station device 1 has a switch 12, a transmission and reception system part 13, a switch controller 15, an RSSI measurement part 32, and a pattern decision part 34. The switch 12 switches over combinations of a plurality of antennas 10 to form a plurality of directivity antenna patterns oriented in different directions or a non-directivity antenna pattern. The switch controller 15 controls the switch 12 to make a signal be received using desired directivity antenna patterns. The RSSI measurement part 32 measures reception strength of each signal received using the directivity antenna patterns. The pattern decision part 34 decides an antenna pattern whose reception strength becomes the maximum based on the measurement result of the reception strength as an antenna pattern to be utilized in communication with a mobile station.