PROBLEM TO BE SOLVED: To improve various functions such as a walking assistant function in a one-leg type walking assistant machine based on passive walking.SOLUTION: A one-leg type walking assistant machine 1 is an assistant machine 1 mounted on one leg of a user U and assisting walking, and includes: a waist mounting part 2 mounted on one waist side part U31； a thigh link part 3 arranged at the lateral side of the thigh U11； a lower thigh link part 4 arranged at the lateral side of the lower thigh U12； a lower thigh mounting part 5 mounted on the lower thigh U12 and attached to the lower thigh link part 4； a waist joint part 6 connecting an upper end 3a and the waist mounting part 2 while the thigh link part 3 is rockable in a front and rear direction with the upper end 3a as a center； a knee joint part 7 connecting an upper end 4a and a lower end 3b while the lower thigh link part 4 is rockable with the upper end 4a as a center in a range of &le；180° of an angle at a rear side between the thigh link part 3 and the lower thigh link part 4； and a thigh contacting part 8 attached to the thigh link part 3 to be interposed between the thigh link part 3 and the thigh U11.
