A confined space estimation system, and a confined space estimation method capable of accurately confirming a confined space formed in the event of a disaster, estimates a confined space comprising a storage device which stores information indicating a geographical space, and a processor which divides the geographical space into grids. Based on location information sent from a terminal, the processor periodically aggregates a number of terminals within the grids or a number of terminals that passed through boundaries between the grids, extracts grids or boundaries in which the aggregated number of terminals is a predetermined number and in which there is no change in the aggregated number of terminals, determines whether the extracted grids or boundaries can be linked to form an annular shape, and, if the annular shape can be formed, estimates a geographical space configured from the grids within the formed annular shape as the confined space.