What is Art on the street? Is it a series of artworks or activities performed on the street? In other words, does “art on the street” refer to “Street Art” such as street performance, happening, graffiti, or wall-painting, or does it refer to “Street Furniture” which is related to “City Design” or “Environmental Design”? In a formal sense, they all belong to Art on the street. However, in this paper, I would like to use Art on the street in an even broader sense. To me, “the street” is a metaphor of “environment.” Thus Art on the street is the art related to environment; it is an environment art. Art on the street attests the expansion of the concept of art and shows a new possibility of contemporary art. It is a promising new concept of art, but we cannot ignore the misapplication of the concept that we can find at the crossroad of Art on the street and “city beautification.” Of course, Art on the street can and sometimes needs to beautify the city. However we still need to ask how to contribute to the city beautification with Art on the street and how to validate such a practice. City space is, most of all, a space that people live in. It sounds a cliché, but it is worth repeating to better understand Art on the street. When we consider the city space in terms of its system or organization, we often overlook that it is the space in which people live, and which people create. Art on the street concerns not the city itself, but the space in which people live and make relations for each other. Without taking this into account, Art on the street becomes a mere means to ‘embellish’ the city and falls prey to the logic of capital. In this paper, I critically reviewed the problems such as City Development, Spectacularization, City Environmental Design, Public Interest and City Museum. I intended to emphasize that Art on the street is produced in the cultural space of city, but it also tends to break the mold of the cultural space and seeks a new possibility. Some might argue that my claims are unrealistic because Art on the street is not an idea but a practice. While humbly accepting the objection, I hope my critical suggestions guide a more productive direction to continue our discussions of Art on the street.