This writing made a survey on the subject of one of the unfair labor practices, ‘union shop Agreement.’ There have been disputes over the legality and justifiability of the union shop agreement in terms of the laborers right not to unite or to choose a union of their own favor even before the revised legislation of the multiple unions permission. Apart from those two traditional concerns over the justifiability of a union shop agreement, the revised legislation of the multiple unions under the current ‘Trade Union and Labor Relations Adjustment Act’ made it necessary to modify the union shop regulations to be adjusted to the revision of the act. According to the article 81 of the ‘Trade Union and Labor Relations Adjustment Act’, it is forbidden to make it a condition of employment that the worker abstain from joining or withdraw from a union or join a particular union. However, in cases where a union represents more than two-thirds of laborers working in the same business and the union establishes a collective agreement with an article of 'union shop' with the employer, then a person can be employed on condition that he or she will become a member of the union. In addition to this, the current law added another regulation to the above union shop article. The employer may not put the laborer in any disadvantageous position in terms of status, on the ground that the worker has been expelled from the union or has with drawn from the union to organize a new union or to join another union. This revision was made to be in accordance with the multiple union permission. Through this revision, the new law seems to accommodate the argument of the laborers' right to work as well as their right to choose a union. In this writing other relevant legal matters were also reviewed. Union shop related legal matters such as the expulsion of a union member, union's right to choose its members, and employer's duty to fire a laborer under the union shop agreement were dealt with in the writing. And finally, I want to add up that more agency shop agreements may be established under the multiple unions system in the future.