The present invention provides an apparatus, method and program for alarming abnormality in tire air-pressure which detects abnormality of a tire even under unusual conditions such as offset load on a vehicle or providing a snow chain on one wheel. The apparatus, method and program for alarming abnormality in tire air-pressure include means of comparing rotational wheel velocities of respective tires provided on a vehicle and detecting whether or not rotational wheel velocity of one wheel is slower than those of other wheels by comparing rotational wheel velocities of respective tires provided on a vehicle.