As a walking assistive device, one of major goals should be reduce wearer's metabolic cost as much as possible. Toward this goal, this paper presents the preliminary study on a new soft wearable robotic suit for ankle and hip assistance for daily life activities. The presented robotic suit is lightweight, and it almost does not restrict the lower limb motion range. In addition, its structure is simple, and thus wearers can easily take the device on and off by themselves. Experimental results on two young subjects show that the robotic suit reduced metabolic cost with averaged reductions of 10.2 % and 6.8 %, respectively, by not drastically disrupting the normal walking biomechanics of the subjects.