An offset estimation device for estimating an offset of magnetic data to be outputted from a tri-axis geomagnetic detection part, comprising: a first rotation axis calculation part being configured to obtain magnetic data at a first clock time and magnetic data at a second clock time, both of which are outputted from the geomagnetic detection part, and first rotation amount data being set as data in accordance with a rotation amount of the geomagnetic detection part in a time period between the first clock time and the second clock time, the first rotation axis calculation part being configured to, in a coordinate space containing respective axial components of the magnetic data to be outputted from the geomagnetic detection part as coordinate values, calculate a first rotation axis in transition from a coordinate value based on the magnetic data at the first clock time to a coordinate value based on the magnetic data at the second clock time on the basis of the magnetic data at the first clock time, the magnetic data at the second clock time and the first rotation amount data in the time period between the first clock time and the second clock time; a second rotation axis calculation part being configured to obtain magnetic data at a third clock time and magnetic data at a fourth clock time, both of which are outputted from the geomagnetic detection part, and second rotation amount data being set as data in accordance with a rotation amount of the geomagnetic detection part in a time period between the third clock time and the fourth clock time, the second rotation axis calculation part being configured to, in the coordinate space containing the respective axial components of the magnetic data to be outputted from the geomagnetic detection part as coordinate values, calculate a second rotation axis in transition from a coordinate value based on the magnetic data at the third clock time to a coordinate value based on the magnetic data at the fourth clock time on the basis of the magnetic data at the third clock time, the magnetic data at the fourth clock time and the second rotation amount data in the time period corresponding to the meantime between the third clock time and the fourth clock time; and an offset estimation part being configured to estimate the offset of the magnetic data of the geomagnetic detection part on the basis of a coordinate value with minimum spatial distances to the first rotation axis and the second rotation axis. a first rotation axis calculation part being configured to obtain magnetic data at a first clock time and magnetic data at a second clock time, both of which are outputted from the geomagnetic detection part, and first rotation amount data being set as data in accordance with a rotation amount of the geomagnetic detection part in a time period between the first clock time and the second clock time, the first rotation axis calculation part being configured to, in a coordinate space containing respective axial components of the magnetic data to be outputted from the geomagnetic detection part as coordinate values, calculate a first rotation axis in transition from a coordinate value based on the magnetic data at the first clock time to a coordinate value based on the magnetic data at the second clock time on the basis of the magnetic data at the first clock time, the magnetic data at the second clock time and the first rotation amount data in the time period between the first clock time and the second clock time; a second rotation axis calculation part being configured to obtain magnetic data at a third clock time and magnetic data at a fourth clock time, both of which are outputted from the geomagnetic detection part, and second rotation amount data being set as data in accordance with a rotation amount of the geomagnetic detection part in a time period between the third clock time and the fourth clock time, the second rotation axis calculation part being configured to, in the coordinate space containing the respective axial components of the magnetic data to be outputted from the geomagnetic detection part as coordinate values, calculate a second rotation axis in transition from a coordinate value based on the magnetic data at the third clock time to a coordinate value based on the magnetic data at the fourth clock time on the basis of the magnetic data at the third clock time, the magnetic data at the fourth clock time and the second rotation amount data in the time period corresponding to the meantime between the third clock time and the fourth clock time; and an offset estimation part being configured to estimate the offset of the magnetic data of the geomagnetic detection part on the basis of a coordinate value with minimum spatial distances to the first rotation axis and the second rotation axis.