The judgment below is reversed, and the case is remanded to Busan High Court.

The grounds of appeal are examined (to the extent of supplement in case of supplemental appellate briefs not timely filed).

1. “Occupational disease” included in “occupational accident” under Article 5 subparag. 1 and Article 37 of the Industrial Accident Compensation Insurance Act refers to a disease caused by the worker’s handling of, or being exposed to, harmful or dangerous factors in the course of performing his/her duties, a disease caused by occupational injury, or any other disease caused by the worker’s occupational injury in the course of performing his/her duties, which is caused by the worker’s occupational injury in the course of performing his/her duties, and thus, there must

However, even if the main cause of the disease is not directly related to the performance of duties, if at least the overwork or stress overlaps with the main cause of the disease and causes or worsens the disease, it can be deemed that there is a causal relationship among them. The causal relationship does not necessarily have to be proved clearly in medical and natural science, and in light of all the circumstances, there is proof even if there is a proximate causal relationship between duties and the disease.

In addition, the basic disease or existing disease that can normally work at ordinary times is caused by excessive work and is rapidly aggravated at the natural progress speed, etc. shall be included in the case where there is proof. In this case, whether there is a causal relationship with work, disease, or death should be determined based on the health and physical conditions of the worker concerned, not the average person.

(see, e.g., Supreme Court Decision 2011Du30014, Apr. 13, 2012). Overwork or stress refers to not only derived from the original work of an employee, but also to overwork or stress arising from the employer’s direction or from the direction of the employer.