Previous studies mainly examined individual and family factors affecting Japanese fathers' involvement in child care. Along with these factors, we examine how work-related factors such as father-friendly environment at work, workplace's accommodation of parental needs, job stress, and autonomy are associated with Japanese men's participation in child care. Using 2010 data collected from Japanese fathers with preschool children ("N" = 1,317), a theoretical model is tested on men who work for large or small/medium companies. We find that company's accommodation of parental needs and job autonomy increase child care involvement of fathers in medium/small companies, and job stress reduces such involvement among men in large companies. Implications of these findings are discussed in light of recent public attention on child caring fathers in Japan. (Contains 3 tables and 1 figure.)