A mobile terminal device (1) includes a first displacement detection unit (11) configured to detect a displacement value associated with movement in an up-and-down direction of the mobile terminal device, a second displacement detection unit (12) configured to detect a displacement value associated with movement or turning in a predetermined direction of the mobile terminal device, a walking posture reference locus storage unit (13) configured to store a locus serving as a reference in relation to a walking posture, a characteristic displacement timing extraction unit (14) configured to extract a timing of a predetermined characteristic displacement appearing at every step based on detected upward and downward displacement values at a plurality of timings, a locus calculation unit (15) configured to select extracted successive walking timings, and to calculate a locus caused by walking of the selected walking timings based on a displacement value detected by the second displacement detection unit, and a walking posture determination unit (16) configured to determine whether the calculated locus satisfies the reference in relation to the walking posture stored in the walking posture reference locus storage unit, whereby, a locus of a walking posture can be efficiently obtained.
