Abstract
In the retail industry in Japan, corporate managers have widely employed part-time workers for the purpose of cutting labor costs, thus expanding these workers' occupational field. Trade unions have also accepted the expansion, leading to a certain degree of improvement in working conditions for part-time workers. As a result, part-time workers' skills have increased and they have assumed administrative roles, but their working conditions have not been better than regular employees working in the same position. This suggests that many conflicting relationships may emerge among employees due to the expansion of the part-time occupational field. This article uses a retail business as its focus to analyze the institutional and historical expansion and transformation of the part-time occupational field in relation to both the conditions and job training system for regular employees, while also considering the logic of the trade union that has boosted this expansion. The findings show that, with the extension of the part-time occupational field, the job training of regular employees has become a contentious issue in industrial relations and trade unions need to create new principles for wage determination.
