A device and a method that permit easy and accurate determination of a walking condition regardless of differences in foot landing points on soles or lengths of legs of a walker are provided. According to this device, a measuring device measures a parameter indicating a displacement speed or a displacement acceleration of a bottom end portion of one leg with respect to a bottom end portion of the other leg of the walker. A first storage device stores patterns of plots corresponding to parameters and walking conditions of the walker. A generating device generates plots defined in the determination space by parameters measured by the measuring device. A determining device determines walking conditions of the walker on the basis of the patterns of the plots stored and retained in conjunction with the walking conditions by the first storage device and the patterns of the plots generated by the generating device.