The potential of a graphite electrode in a charged lithium ion battery is sufficiently low to induce reduction of the electrolyte solution. By reduction during the first charging (intercalation of Li+ into graphite), a surface film (solid electrolyte interphase (SEI)) forms on the graphite. The SEI passivates further reduction, enabling stable charge/discharge cycles. In the present study, the effect of chronoamperometric pretreatment before the first intercalation on the property of the SEI was studied by measurements of the concentration of electrolyte salt in deep narrow spaces between highly oriented pyrolytic graphite (HOPG) and lithium electrodes using in situ ultrafine probe Raman spectroscopy and impedance spectroscopy. When pretreatment at 0.9 V vs lithium for 20 hours was applied, the resistance of the SEI was enhanced, but the resistance for charge transfer and capacitance at the surface of the graphite decreased, compared with those for the battery without pretreatment. The concentration of the electrolyte salt in the battery without pretreatment clearly increased and decreased during intercalation and de-intercalation, respectively. However, for the battery with pretreatment, the concentration changes were suppressed. The results demonstrate the importance of pretreatment and provide useful information for the development of effective pretreatment processes to enhance battery performance. (C) 2017 The Electrochemical Society. All rights reserved.