The purpose of the present invention is to provide a pupil expander capable of being safely arranged without damaging an iris and capable of maintaining a sufficiently expanded state of a pupil during ophthalmologic surgery such as cataract surgery. This pupil expander 1 is used for maintaining a pupil P in an expanded state during cataract surgery and include: four arm sections 10 serially arranged so as to form a circular shape and coupling sections 20 each made of a plastic material and configured to connect end sections of adjacent arm sections 10. The end sections of adjacent arm sections 10 are connected to each other by the coupling section 20 made of a plastic material and, as a result, the overall shape of the pupil expander 1 changes inside an eye on the basis of deformation of the coupling section 20 and the overall shape of the pupil expander 1 is maintained after the deformation. As a result, the pupil expander can be safely arranged without damaging an iris I and a sufficiently expanded state of the pupil P can be maintained.
