This study aims to analyze the characteristics of household's decision behavior of auto ownership, usage, worker's commuting distance, and Commuting mode. In order to investigate the complicated interrelationship among these decisions, we developed a simultaneous equation model to reflect the choices of commuting distance and auto ownership. We also developed a mixed discrete/continuous choice model to reflect the choices of auto ownership, commuting mode, and auto usage. Empirical analysis was performed usine household survey data. The results indicated that the choices of commuting distance and auto ownership are indeed mutually related, and the choices of auto ownership, usage, and commuting mode are interrelated to each other as well.