Preparation of base metal electrodes on low temperature co-fired ceramic (LTCC) by an inkjet method was investigated. CuO powder containing water based ink was printed onto LTCC green sheets by an inkjet method. Prior to the printing, the LTCC green sheets were treated with oxygen plasma. The results of XPS showed that the number of hydrophilic functional groups on the surface of the sheets was increased and the wettability of the surface was improved. The green sheets printed with CuO ink were stacked and co-fired under 3% H2-N2 atmosphere. From the results of XRD measurement and EPMA for the cross section of LTCC, it was clarified that CuO was reduced to metal Cu by firing, and no reaction and diffusion between Cu and LTCC were observed. The volume resistivity of Cu in the multilayer ceramics was approximately 18 μΩ·cm. The possibility of preparation of base metal electrodes on LTCC by inkjet method using metal-oxide-containing ink was indicated.