NGC 3506 is a spiral galaxy in the constellation Leo. It is located at a distance of circa 300 million light years from Earth, which, given its apparent dimensions, means that NGC 3506 is about 115,000 light years across. The galaxy has two main spiral arms, with high surface brightness, which can be traced for half a revolution before they fade. One arm splits into four spiral arcs.

It is an isolated galaxy.

Three supernovae have been observed in NGC 3506: