A self-running vacuum cleaner comprises a homing mode of following a back of a
user with receiving a signal from a light emitting means or a transmitting means
of a position indicator means held by the user, an instruction operation mode,
in which the user instructs a cleaning area to the self-running vacuum cleaner,
and an execution mode for cleaning up the cleaning area instructed. When the self-running
vacuum cleaner operates under the homing mode or the instruction mode, a signal
from the light-emitting means or the transmitting means is received by a receiver
means attached on a periphery portion of a measuring means, which is provided in
an upper portion of the vacuum cleaner. Comparing the signals from the two (2)
receiver means in strength thereof determines the distance and the direction from
the position indicated by the light-emitting means or the transmitting means up
to the vacuum cleaner.