As the Disability Discrimination Act was established in Korea, the discrimination in usage and accessibility of electronic information against the disabled without proper reason has been forbidden. Thus, the Government stipulated web accessibility in 2008 and indicated the range of application based on types of institutions. Therefore, the institutions are obligated to follow this guideline by certain time; a public institution by 2009, an educational institution by 2011, and other institutions by 2015. This study first investigated the web accessibility of national museums, which are public institutions. The result was that most of national museums follow only the parts of the guideline such as provision of alternative text and logical contents. The museums did not provide the substitute methods of multimedia contents, frame title, and a system that every function is operated only by keyboard. Furthermore, the thesis found some points needed but not on the guideline such as the usage of well-explainable images, a clear and short text, and a supply of alternative text when using optional services like mailing service and signing a membership. In addition, the study suggested that major Korean national should provide closed captions, manuscripts, or sign languages for the hearing-impaired when showing multimedia contents, reflecting a growing trend of video multimedia contents.