A portable device includes an acceleration sensor capable of detecting accelerations in three-axis directions. When a GPS radio wave is receivable by a GPS module, the portable device stores, using an MCU, a correlation between a body vibration frequency detected by the acceleration sensor and speed information grasped by processing a signal included in the GPS radio wave in a flash ROM. When a reception state of the GPS radio wave does not satisfy a predetermined standard, the portable device estimates running speed using the MCU on the basis of the body vibration frequency detected by the acceleration sensor 38 and the correlation stored in the flash ROM.
