A travelling state determining device which determines a travelling state of a user wearing the travelling state determining device, comprising: an acceleration sensor adapted to detect accelerations of a plurality of directions and to output data indicating the accelerations in the plurality of directions; a triaxial terrestrial magnetism sensor adapted to provide an output from which the direction of magnetic north can be specified; a travelling determining unit adapted to determine between a state of travelling and stopping; a direction setting unit adapted a) to obtain the direction of the travelling state determining device based on the output of the acceleration sensor and of the triaxial terrestrial magnetism sensor, b) to set as a vertical direction a direction in which a gravitational acceleration is always provided in the output of the acceleration sensor, c) to set as a travelling direction an acceleration direction of the detected acceleration by detecting an acceleration of the acceleration sensor that expresses starting and stopping of a transportation option; and d) to set as a lateral direction a direction which is perpendicular to the vertical direction and the travelling direction; and a specific acceleration extracting unit adapted to extract a predetermined frequency component of an acceleration of a lateral direction component, based on the settings of the direction setting unit; and a state determining unit adapted to determine, during a period which the travelling determining unit determines as travelling, between a state of travelling by the transportation option which travels on rails and a state of travelling by the transportation option which travels on roads by comparing the level of the acceleration which is extracted by the specific acceleration extracting unit toa second threshold value to determine between the states based on the comparing result; wherein the travelling determining unit is adapted to determine between travelling and stopping based on a result of comparing a level of an acceleration of a vertical direction component to a first threshold value, wherein the vertical direction component is a frequency component included in a range of 1 Hz to 3 Hz in the output of the acceleration sensor. an acceleration sensor adapted to detect accelerations of a plurality of directions and to output data indicating the accelerations in the plurality of directions; a triaxial terrestrial magnetism sensor adapted to provide an output from which the direction of magnetic north can be specified; a travelling determining unit adapted to determine between a state of travelling and stopping; a direction setting unit adapted a) to obtain the direction of the travelling state determining device based on the output of the acceleration sensor and of the triaxial terrestrial magnetism sensor, b) to set as a vertical direction a direction in which a gravitational acceleration is always provided in the output of the acceleration sensor, c) to set as a travelling direction an acceleration direction of the detected acceleration by detecting an acceleration of the acceleration sensor that expresses starting and stopping of a transportation option; and d) to set as a lateral direction a direction which is perpendicular to the vertical direction and the travelling direction; and a specific acceleration extracting unit adapted to extract a predetermined frequency component of an acceleration of a lateral direction component, based on the settings of the direction setting unit; and a state determining unit adapted to determine, during a period which the travelling determining unit determines as travelling, between a state of travelling by the transportation option which travels on rails and a state of travelling by the transportation option which travels on roads by comparing the level of the acceleration which is extracted by the specific acceleration extracting unit toa second threshold value to determine between the states based on the comparing result; wherein the travelling determining unit is adapted to determine between travelling and stopping based on a result of comparing a level of an acceleration of a vertical direction component to a first threshold value, wherein the vertical direction component is a frequency component included in a range of 1 Hz to 3 Hz in the output of the acceleration sensor.