Disclosed is a side door for a construction machine which is openably and closably mounted on a side of an engine room. A side door for a construction machine according to the present invention comprises: a door frame mounted on a side of an engine room; a side door which is mounted on the door frame to be vertically movable in order to open and close an opening formed in the door frame so as to communicate with the engine room; a rotary pin rotatably supported on an inner upper portion of the door frame; and a link which, when the side door is rotated around the rotary pin, opens and closes the side door upwards and downwards by moving the side door in rectilinear and curvilinear motions, wherein the link has an upper end connected to the rotary pin and a lower end connected to any position on an inner side of the side door; and a gas spring which rotates the link clockwise or counterclockwise when the gas spring is expanded or contracted to open or close the side door, wherein the gas spring has one end rot
