This study aims to investigate and analyze the plan and structural system of 4 kan(間) by 4 kan(間) square church built in early 20th century. At that time, three kinds of traditional wooden structure church had been built under the circumstances of transitional era : Basilica style such as Ganghwa Anglican Church, ‘ㄱ’ shaped style such as Keumsan Church and 4×4 Square style such as Bukok Church and Jacheon Church that are concerned in this study. Traditional plans and structural system were mixed with new religious function and transformed into korean peculiar style. 4×4 Square style is a residual product in that process. Despite of it, little concerns on it till now. The results of this study are described as follows. 1. The plan of these 4×4 square churches is divided into three areas : cathedra(1×1), attendance(4×2), and intermediation(4×2). The location of cathedra is commonly the opposition part of main gate and projected out of the building. Attendance area was also divided into two, man and woman, because of keeping a distance with each other. 2. The structural system of these 4×4 square churches are somewhat different because of their size and roof style. In the case of Bukok church, 4×4 square fall off 3×3 and 2×2 gradually and turn into paljak(八作) roof, which enable us to get in traditional entering methods. On the contrary, Jacheon church use hipped roof but almost alike pyramidal roof, which could make us not to recognize entering in the aspect of gable part.