The purpose of this study is to suggest the tendency and problems through a time-series analysis of legal management standards of the outdoor advertisement landscape. Moreover, based on the analysis result of the problem, a direction for improvement was suggested. Changes in management standards over 30 years from 1991 to 2021 were analyzed for each of the eight elements of type, shape, quantity, size, display location, color, material, and lighting for which legal management standards were established. Although the outdoor advertisement landscape formed by a cluster of outdoor advertisements is an important element of the urban landscape, in Korea, it is being criticized as the main culprit in lowering the urban landscape as more and larger outdoor advertisements are installed. Among the analysis elements, it was confirmed that there was no significant change in the management standards for type, form, material, and lighting, but the quantity, size, and location were continuously relaxed. Not only specific figures such as number and area, but also mitigation conditions and targets have been relaxed. In particular, after the introduction of digital advertisements in 2016, the size, location, application area, and protrusion width have been expanded. Although digital advertisements have a very large impact on the urban landscape, management standards were relaxed without careful consideration. It is necessary to seek specific solutions through in-depth follow-up studies for each analysis element.