1. An output apparatus, comprising one or more processors configured to function as a plurality of sections comprising: a moving image acquiring section that receives via a transmission path a moving image obtained by capturing a monitored area; a moving object extracting section that extracts a moving object in the moving image received by the moving image acquiring section; an object area identifying section that identifies an object area, which is an area occupied by the object extracted by the moving object extracting section in each moving image component image in a plurality of moving image component images included in the moving image received by the moving image acquiring section; a moving image component image selecting section that selects a plurality of moving image component images in which the object areas identified by the object area identifying section are not in positions that overlap with one another from among the plurality of moving image component images included in the moving image received by the moving image acquiring section; an image generating section that generates a single synthesized image by superimposing images that include a plurality of object areas included in each moving image component image in the plurality of moving image component images selected by the moving image component image selecting section; and an output section that outputs the synthesized image generated by the image generating section, wherein the moving image component image selecting section selects a plurality of moving image component images in which the object areas identified by the object area identifying section are not in positions that overlap with one another from among the plurality of moving image component images included in a moving image of a first period in the moving image received by the moving image acquiring section, the image generating section generates a single synthesized image by superimposing the images that include the plurality of object areas included in each moving image component image in the plurality of moving image component images selected by the moving image component image selecting section, the output section outputs the single synthesized image generated by the image generating section as the image representing the moving image of the first period instead of the plurality of moving image component images included in the moving image of the first period, the moving image component image selecting section selects a first group of moving image component images in which the object areas identified by the object area identifying section are not in positions that overlap with one another from among the plurality of moving image component images included in the moving image of the first period in the moving image received by the moving image acquiring section and selects a second group of moving image component images in which the object areas identified by the object area identifying section are not in positions that overlap with one another from among at least a portion of the moving image component images in the plurality of moving image component images included in the moving image of the first period and from among the plurality of moving image component images included in the moving image of a second period that follows the first period, the image generating section generates a first synthesized image by superimposing the images that include the plurality of object areas included in each moving image component image of the first group and generates a second synthesized image by superimposing the images that include the plurality of object areas included in each moving image component image of the second group, and the output section outputs the first synthesized image and the second synthesized image generated by the image generating section as the images representing the moving images of the first period and the second period, respectively, instead of the plurality of moving image component images included in the moving images of the first period and the second period.