Based on an experimental fact that surface wave plasmas excited by strongly coupled microwave through thin dielectric windows show nearly perfect absorption of microwave and, after diffusion, form a widely uniform dense plasma. A plasma with an uniformity of 5% over an area of 50 cm 60 cm was produced. The plasma produced by application of 2400 W total microwave power gives 1 1011 cm-3 in density and 1.5 eV in electron temperature.