Lithium ion batteries have attracted much attention due to their high power density. The change in concentration of salt in the electrolyte solution and local shortage of electrolyte solution in batteries cause serious degradation of battery performance. In this work, in situ Raman spectroscopy of the electrolyte solution at different positions in a laminate lithium ion battery (a typical practical battery) was simultaneously conducted by using ultrafine multi-probes. Eight probes were aligned in deep narrow spaces between two electrodes at intervals of about 2.5 mm in a plane parallel to the surfaces of electrodes. The concentration changed differently at the positions during charging and discharging. In addition, local dry up and local refilling of the electrolyte solution were observed. These phenomena were sometimes observed at the same time at the positions of two adjacent probes, indicating that the phenomena occurred in a millimeter scale. The method used in this study is useful for in situ analysis of the electrolyte solution in deep narrow spaces in other electrochemical devices under conditions close to those in practical devices.