The electrochemical properties of Li2SiS3 were investigated in a solid electrolyte. Li2SiS3 was converted to elemental Si, and the resultant Si was formed into Si–Li alloy in the reduction process; however, the reverse reaction was not completed due to the loss of electronic conduction upon reoxidation. FeS was dispersed as a conductive additive in Li2SiS3 films by pulsed laser deposition (PLD). The addition allowed successive reactions to proceed at a large capacity with small capacity-fading during the cycling process in spite of the small FeS fraction. This result indicates that Li2SiS3 +FeS thin film is a promising anode for solid-state lithium batteries.