PROBLEM TO BE SOLVED: To provide a portable information device capable of evaluating whether a device attitude is stable and a stable walk is taken.SOLUTION: A portable information device includes: an acceleration sensor capable of measuring acceleration in the form of a vector quantity; axial distribution determination means of determining whether a plurality of measured acceleration vectors are possibly distributed conically; cone evaluation means of approximating a distribution of the plurality of acceleration vectors for which the axial distribution determination means makes a true determination with a cone, and evaluating the narrowing level of the cone showing how the cone narrows as stability of a walk. Preferably, the portable information device further includes: walk estimation means of detecting candidate acceleration variation in the walk of data on the measured acceleration vectors; and walk evaluation means of evaluating walk adequacy showing whether the acceleration variation is caused by the wa
