Solid-state lithium batteries fabricated by thin film technology are attracting attention as micro-batteries. The thin film battery structure means that they have a small discharge capacity, therefore, it is necessary to increase the cell capacity per unit area of the cathode film for practical use. We fabricated thin film batteries with fairly thick MoO3-x cathode films, which had a larger specific capacity than other cathode films (e.g., LiMn2O4 film). We then examined the cell performance of our thin film batteries. When the discharge current density was 10 muA/cm(2), the batteries had discharge capacities of 290 muA h/cm(2) per unit area, and this value is the highest among typical thin film batteries reported to date.