The purpose of this paper is to show the realization of passive walking of a biped robot Emu that is composed of 1 body and 2 legs. In the beginning of this paper, we formulate the problem and analyze the stability of the walking with attitude control of a body. The walking is called ""semi-passive walking"". We show, next, a numerical simulation on the semi-passive walking. Finally, we show some experimental results to verify a validity of the semi-passive walking and the analysis.