  We conducted a series of beam tests of prototype TPCs for the International
Linear Collider (ILC) experiment, equipped with an MWPC, a MicroMEGAS, or GEMs
as a readout device. The prototype operated successfully in a test beam at KEK
under an axial magnetic field of up to 1 T. The analysis of data is now in
progress and some of the preliminary results obtained with GEMs and MicroMEGAS
are presented along with our interpretation. Also given is the extrapolation of
the obtained spatial resolution to that of a large TPC expected for the central
tracker of the ILC experiment.
