The stop detecting module
40 acquires a stop detection acceleration [a
x(AN)
s, a
y(AN)
s, a
z(AN)
s] comprised of a sum of the movement acceleration frequency component and the noise frequency component of the sensor coordinate system acceleration [a
x
s, a
y
s, a
z
s]. The stop detecting module
40 stores, in advance, thresholds (≠0) for detecting a stop, for a front-and-rear direction component a
x(AN)
s and a left-and-right direction component a
y(AN)
s of the stop detection acceleration [a
x(AN)
s, a
y(AN)
s, a
z(AN)
s] When stop detecting module
40 detects that the front-and-rear direction component a
x(AN)
s and the left-and-right direction component a
y(AN)
s are both below the threshold for detecting the stop, it determines that the movable body is stopped and outputs stop detection data to the speed/traveling-angle calculating module
30. After the speed/traveling-angle calculating module
30 acquires the stop detection data, it sets the traveling speed V
x in the front-and-rear direction=0 and calculates a traveling pitch angle θ, based on Equation (18B) described above, according to the setting.