A surrounding area monitoring device for monitoring an area around a work machine, comprising: a display device; a worker position detection unit (10a,10b,10c) that detects a position of a worker working around the work machine; image capturing units (13a,13b, 13c) mounted at the work machine, which obtain surrounding area images by capturing images of areas around the work machine; an image conversion unit that converts the surrounding image of the area around the work machine, obtained by the image capturing units (13a, 13b, 13c), to a bird's eye view image of the work machine; an image generation unit that generates a monitor image based upon the bird's eye view image resulting from conversion via the image conversion unit and the position of the worker detected by the worker position detection unit (10a,10b,10c); a display control unit that displays the monitor image at the display device; a decision-making unit that makes a decision as to whether or not the position of the worker is located within a monitoring area set in advance; and a plurality of work machine condition detection units that detect an attitude of the work machine including a work machine traveling speed at which the work machine is traveling or drive conditions of the work machine, characterized in that: the image generation unit generates a plurality of monitor images which show conditions within monitoring areas with varying ranges based upon results of the decision made by the decision-making unit or information provided from at least one of the work machine condition detection units, the monitoring areas being set around the work machine; and the plurality of monitor images include an immediate range display image showing conditions in an immediate area set around the work machine and a wide range display image showing conditions in a wide area containing the immediate area, also set around the work machine. a display device; a worker position detection unit (10a,10b,10c) that detects a position of a worker working around the work machine; image capturing units (13a,13b, 13c) mounted at the work machine, which obtain surrounding area images by capturing images of areas around the work machine; an image conversion unit that converts the surrounding image of the area around the work machine, obtained by the image capturing units (13a, 13b, 13c), to a bird's eye view image of the work machine; an image generation unit that generates a monitor image based upon the bird's eye view image resulting from conversion via the image conversion unit and the position of the worker detected by the worker position detection unit (10a,10b,10c); a display control unit that displays the monitor image at the display device; a decision-making unit that makes a decision as to whether or not the position of the worker is located within a monitoring area set in advance; and a plurality of work machine condition detection units that detect an attitude of the work machine including a work machine traveling speed at which the work machine is traveling or drive conditions of the work machine, characterized in that: the image generation unit generates a plurality of monitor images which show conditions within monitoring areas with varying ranges based upon results of the decision made by the decision-making unit or information provided from at least one of the work machine condition detection units, the monitoring areas being set around the work machine; and the plurality of monitor images include an immediate range display image showing conditions in an immediate area set around the work machine and a wide range display image showing conditions in a wide area containing the immediate area, also set around the work machine. the image generation unit generates a plurality of monitor images which show conditions within monitoring areas with varying ranges based upon results of the decision made by the decision-making unit or information provided from at least one of the work machine condition detection units, the monitoring areas being set around the work machine; and the plurality of monitor images include an immediate range display image showing conditions in an immediate area set around the work machine and a wide range display image showing conditions in a wide area containing the immediate area, also set around the work machine.