The Siphnian Treasury was a building at the Ancient Greek cult centre of Delphi, erected to host the offerings of the polis, or city-state, of Siphnos. It was one of a number of treasuries lining the "Sacred Way", the processional route through the Sanctuary of Apollo, erected to win the favor of the gods and increase the prestige of the donor polis. It was one of the earlier surviving buildings of this type, and its date remains a matter for debate, with the most plausible date being around 525 BC. Until recently it was often confused or conflated with the neighbouring Cnidian Treasury, a similar but less elaborate building, as the remains of the two had become mixed together and earlier theoretical reconstructions used parts of both.

Delphi, in legend previously called Pytho (Πυθώ), was an ancient sacred precinct and the seat of Pythia, the major oracle who was consulted about important decisions throughout the ancient classical world. The ancient Greeks considered the centre of the world to be in Delphi, marked by the stone monument known as the Omphalos of Delphi (navel).