This chapter deals with a prerequisite that scientific accident investigation is being conducted, focuses on the Swiss cheese model (SCM) which is widely used in marine domain, both historical background of the accident model and describes the field of application of the accident model. Once an accident like these occurs, many lives, property, environment, reputation of the company and urban function are lost and serious damage is caused; therefore, prevention of accidents is an important issue in all sectors of industries. The accident model is important as a tool to understand phenomena, such as accidents or potentially dangerous system behavior, and as a tool to share contributing factors when discussing accidents with other people. The sequential accident model is represented by the domino theory advocated by Heinrich, and it is also referred to as the domino model. The SCM as a representative of epidemiological accident model was developed in 1990.