The purpose of this final project are to identify consumers identity, to analyze the influence of service quality to purchasing decisions of Tawang Jaya train service at PT Kereta Api Indonesia (Persero) DAOP IV Semarang, and identify the most dominnt variable the influence purchasing decisions rail transportation Tawang Jaya at PT Kereta Api Indonesia (Persero) DAOP IV Semarang. The research sampling techniques is purposive sampling. The method of data collection are a libraries study, questionnaire and interview. The analysis method is multiple linier regression. The result shows the all variables has positive and significant impact on the purchasing decisions partially and simultaneously of to reflecf the regression equation which Y=0,161X1 + 0,234X2 + 0.245X3 + 0.195X4 + 0,333X5 + e. The most dominant variable is tangible has value 0,333.