© The Electrochemical Society of Japan, All rights reserved. Lithium distribution in the composite electrode of an all-solid-state lithium battery was analyzed by microbeam-particle-induced X-ray emission and gamma-ray emission techniques. Two kinds of pellet-type cells, incorporating LiCoO2 as the cathode-active material and the superionic conductor Li10GeP2S12 as the solid electrolyte, were prepared: one in the as-prepared state and the other in the charged state. Changes in the lithium distribution near the interface of the composite cathode and separator were visualized by normalizing lithium/cobalt and lithium/germanium intensity. Lithium extraction from LiCoO2 due to charging was confirmed by the decrease in normalized intensity at the cathode composite region. The evaluation of the lithium concentration variation in the composite electrode for the all-solid-state battery during the electrochemical reactions could provide essential information for construction of a favorable composite electrode to enable preparing high-performance all-solid-state lithium batteries.