Delay profile of ultra-wideband impulse-radio (UWB-IR) indoor channel fluctuates for a physical change such as intruder. This paper investigates a human body detection using the UWB-IR in order to protect a house, not a room, because the radio with high range resolution can penetrate into the inner walls and also the reflected paths from human body are discriminated in time domain. The usefulness is experimentally investigated under a scenario which someone intrudes into a typical house with four rooms and walks around.