To provide a stabilization method of origination frequency applicable to a wireless device installed in an environment where temperature variation is extremely large from ultrahigh temperature to ultralow temperature.

The stabilization method of origination frequency in an apparatus comprising a plurality of origination circuits includes a temperature in housing measurement step for measuring the temperature in a housing, a temperature range determination step for determining a temperature range measured from the relation of magnitude between a measured temperature in housing T and predetermined temperatures T0, T1, ..., Tk, ..., Tn, and a circuit selection step for selecting any one of a plurality of origination circuits depending on the temperature range determined in the temperature range determination step. When the temperature in a housing T is in the range of Tk-1≤T<Tk, the circuit selection step selects an origination circuit previously adjusted so that the origination frequency of an originator falls within a desired range in the temperature range.