A running condition detection device includes a GPS receiving unit configured to receive a GPS signal and output a current position, a geomagnetic sensor configured to detect geomagnetism, a direction determination unit configured to obtain a current moving direction based on current positional data and last positional data from the GPS receiving unit, a first bend determination unit configured to compare current moving direction data obtained by the direction determination unit and reference direction data to determine passage of a street corner, a second bend determination unit configured to compare geomagnetic data detected by the geomagnetic sensor and reference geomagnetic data to determine passage of a street corner, and a determination prohibition unit which prohibits the first and second bend determination units from determining passage of a street corner during a given period of time when passage of a street corner is determined by one of the first bend determination unit and the second bend determination unit.