Abstract: An acceleration sensor output processing program for causing a computer to execute a process having generating an outer product of a gravity component vector that is extracted from a sensor value of a triaxial acceleration sensor which is detected during walking by a low pass filter and a swing component vector that is extracted from the sensor value by a high pass filter; obtaining a first value corresponding to a magnitude of the outer product; determining an odd-numbered walking period and an even-numbered walking period of the walking; and generating a magnitude of acceleration in one and the other horizontal directions by inverting a sign of the first value in accordance with a result of the determining.