According to Article 35, paragraph 1, sub-paragraph 5 of the Labor Union Act, the so called ＂domination or interference practices＂ refers to an employer or supervisory employees who represent the employer in exercising the managerial authority improperly influence, impede or restrict the establishment, organization or activities of labor union. However, compare with other unfair labor practices, domination or interference practices can be conducted in various forms. The conductors of domination or interference practices are not particularly the employers, it could be a certain person like supervisor, supervisory employee who represent the employer in exercising the managerial authority, a person resembling supervisory employee who represent the employer in exercising the managerial authority, employee, other labor union member, even an external third party. Therefore, under what kind of circumstances should an employer take the responsibilities? Furthermore, based on Article 36 of the Labor Union Act, the cadre members of a labor union are allowed to have official leaves to handle union affairs during their working hours; nevertheless, if the cadre members of a labor union get bad job-performance evaluation by taking official leaves, could we refer this to an unfair labor practice? Now we are going to go through this case by organizing the current decisions on the Unfair Labor Practices in Taiwan and comparing with the development of theory to bring out the feature of this Decision, then examining the adequacy of this Decision by introducing and analyzing the related laws from Japanese Labor Union Act as a reference (for Article 35, paragraph 1, sub-paragraph 5 of the Labor Union Act). By this article, I hope labors and labor unions could know this issue better and improve their solidarity rights.