The present invention relates to a sliding assembling safety window to prevent a screw for joining a bar to a frame from being exposed to the outside and to reduce time for assembling a safety window by sliding and joining the bar to which a guide part is screwed into the guiderail at the bottom of the frame of a safety window frame; to facilitate the installation of an alarming unit on the frame and the bar on the frame by arranging the detection wire of the alarming unit on a wire insertion groove on the bar into zigzags or by electrically connecting the bars to each other using a connection member; and to prevent intruders from coming into a room from the outside by inserting a screen or a resin panel into a space between the bars.