The present invention relates to a porous media-mediated high speed filtration device for easy backwash, wherein the inflow water to be filtered is guided to an upper portion of the high speed filtration device and is filtered by downflow and porous media are backwashed for maintaining optimum filter efficiency by blocking the flow of inflow water and water to be treated after sensing the level of the inflow water or the change in the flux of the water to be treated, supplying backwash water and/or air by upflow through a backwash equipment to separate pollutants in the porous media by the collision and friction between the porous media by flowing of the porous media through the stream of the backwash water, placing the porous media in a stationary location, and discharging the pollutants through a discharge pipe of the high speed filtration device before the pollutants settle. In addition, the present invention comprises a backwash method of the high speed filtration device using porous media.