Abstract
The article reveals the preconditions for the emergence of a specific visual style and a special genre in the field of poster— a «psychodelic poster» in the 1960s in the United Kingdom.It is established that during the pop art movement, due to the popularity of the idea of replicating, from all branches of British graphic design it was poster that developed the most and got the status of the cult genre that caused the emergence of the so called phenomenon «poster boom». It is argued that it was exactly the poster that allowed to fully reveal the bright opportunities that were opened due to the new technical and artistic means of the pop art movement. The psychodelic posters of the British underground studio «Hapshash & The Colored Coat» have been analyzed as the most striking representative of the pop art movement in British graphic design. Though the pop-art soon declined, it became a prelude of postmodernism in the former avant-garde circles.