It is an object of the present invention to provide an oxygen reduction electrode having excellent oxygen reduction catalysis ability. In a method of manufacturing a manganese oxide nanostructure having excellent oxygen reduction catalysis ability and composed of secondary particles which are aggregations of primary particles of manganese oxide, a target plate made of manganese oxide is irradiated with laser light to desorb the component substance of the target plate, and the desorbed substance is deposited on a substrate facing substantially parallel to the aforementioned target plate.