The Japan Meteorological Agency (JMA) has started the practical service of Earthquake Early Warning (EEW) and a very dense deployment of receiving units is expected in the near future. The receiving/alarm unit of an EEW system is equipped with a CPU and memory and is on-line via the internet. By adding an inexpensive seismometer and A/D converter, this unit is transformed into a real-time seismic observatory, which we are calling a home seismometer. If the home seismometer is incorporated in the standard receiving unit of EEW, then the number of seismic observatories will be drastically increased. Since the background noise inside a house caused by human activity may be very large, we have developed specialized software for on-site warning using the home seismometer. We tested our software and found that our algorithm can correctly distinguish between noise and earthquakes for nearly all the events.