A walking assist device including a waist assembly and at least one leg assembly connected to the waist assembly is provided. The leg assembly includes a thigh stand, a shank stand, a sole, a hip joint, a knee joint and an ankle joint. The hip joint is pivoted to the thigh. The knee joint is pivoted to the thigh stand and connected to the shank stand. The ankle joint includes a flexible plate and an elastic member. The flexible plate includes a first end and a second end opposite to each other. The first end is pivoted to the shank stand directly or indirectly, the second end is connected to the sole, and the elastic member presses the first end of the flexible plate.