The present invention relates to a play mat assembly capable of being changed into various shapes and improving safety. The play mat assembly according to an embodiment of the present invention comprises: a main mat which has a plurality of unit mats formed in a polygonal shape and a loop member of being fixated and coupled to each unit mat with Velcro; and a detachable unit which is combined to the main mat to be detachable and has a hook member hung and combined onto the loop member with Velcro. The unit mat includes a cushion mattress and a cover surrounding the cushion mattress, an opening is formed in the lateral side of the unit mat by cutting the cover, and the loop member is positioned between the cover and the cushion mattress and is exposed through the opening.
