This study is intended to look into the effects of employee's working environment on work loss and productivity in overseas construction sites of Korean construction companies. To achieve this, a survey was empirically carried out to overseas construction site experts. The results were as follows. The weight by 5 loss factors of overseas construction projects showed that project management environment was the highest, followed by construction company environment, owner environment, government support environment and entry country environment, which the biggest work loss factor was the project management section. The weight by loss factors of entry country environment showed that local environment was highest, followed by social environment, economical environment, political environment and cultural environment. In other words, awareness and management of weak social bases, which are not well-institutionalized as properties of most preferred loss, are important in that local environment of new entry countries is the most important thing. As for the above-mentioned findings, the most important project management of overseas construction projects will need to take advantage and have know-how for construction companies' ability to cope with a crisis or the most preferred management and loss prevention of owner environment, government support environment and entry country environment.