Provided is a visualization apparatus for a transparent PEMFC using a transparent window having conditions approximating a real PEMFC. More specifically, the present invention includes a heat-exchange passage heat exchanging a transparent plate of a visualization apparatus with a current collector plate in order to control heat. In order to achieve the above object, the present invention includes: current collector plates each provided at both surfaces of a membrane electrode assembly of a fuel cell and formed with a channel in which reaction gas and products flow; transparent plates provided at an outer surface of the current collector plates and provided with a heat-exchange passage having a fluid flowing therein to be heat-exchanged with the current collector plates; and fixing frames having a visualization window for observing the current collector plates and provided at the outer side of the transparent plates.