  Study on a rectified current induced by active particles has received a great
attention due to its possible application to a microscopic motor in biological
environments. Insertion of an {\em asymmetric} passive object amid many active
particles has been regarded as an essential ingredient for generating such a
rectified motion. Here, we report that the reverse situation is also possible,
where the motion of an active object can be rectified by its geometric
asymmetry amid many passive particles. This may describe an unidirectional
motion of polar biological agents with asymmetric shape. We also find a weak
but less diffusive rectified motion in a {\em passive} mode without energy
pump-in. This "moving by dissipation" mechanism could be used as a design
principle for developing more reliable microscopic motors.
