Reversible deformation of materials may provide new opportunities for creation of artificial muscles and smart actuating systems. Despite many efforts, no attempt has been made to observe the response of polymers at a single polymer chain level, Here, we describe a successful method For isolation of a photoresponsive polymer in a monolayer state via so-called skeletonization, Atomic force microscopic observation clearly revealed a large and reversible light-driven morphological response of dot-shaped nano-films on mica most probably consisting of one polymer chain. The dot films observed here can be regarded as the smallest polymer material in response to stimuli.