Tadasuni is a comune, or municipality, located in the Province of Oristano within the Italian region of Sardinia. It is situated approximately 35 kilometres (22 mi) northeast of Oristano and about 100 kilometres (62 mi) north of Cagliari.
As of December 31, 2004, the municipality covered an area of 4.6 square kilometres (1.8 mi2) with a recorded population of 187 residents.