Resin foam and manufacturing method therefor

Provided is a resin foam having excellent dust resistance, even at high temperatures. The resin foam according to the first embodiment of the present invention is characterized by having a thickness recovery rate (23 DEG C, 1 minute, 50% compression), as defined below, of at least 70%, and a strain recovery rate (80 DEG C, 24 hours, 50% compression), as defined below, of at least 80%. Thickness recovery rate (23 DEG C, 1 minute, 50% compression): the ratio of the thickness 1 second after compression is stopped to the initial thickness, as found by compressing the resin foam to just 50% of the initial thickness thereof at 23 DEG C, maintaining the compression for 1 minute at 23 DEG C, and then stopping the compression. Strain recovery rate (80 DEG C, 24 hours, 50% compression): the ratio of recovered distance to compressed distance as found by compressing the resin foam to just 50% of the initial thickness thereof at 23 DEG C, maintaining the compression for 24 hours at 80 DEG C, returning the temperature to 2