A torso part (2) and a backpack part (6) of a humanoid robot are commonly formed by a shell that defines an inner space that accommodates a heat generating component such as a control computer (31) and a power module (32, 33). The shell comprises an air vent hole (45, 46) provided on one lateral side of the shell, an air inlet hole (47, 48) provided on the other lateral side of the shell and a powered fan (49) provided immediately inside the air vent hole. Because the cooling air can flow laterally across the inner space, the entire part of the heat generating component can contact the air flow, and a uniform cooling effect can be achieved with a minimum power consumption and a minimum noise generation.