Wang Sai Phun (Thai: วังทรายพูน, pronounced [wāŋ sāːj pʰūːn]) is a district (amphoe) in the eastern part of Phichit province, central Thailand.

Tambon Wang Sai Phun, Nong Phra and Nong Pla Lai were separated from Mueang Phichit District and made up the new minor district (king amphoe) Wang Sai Phun on 1 August 1975.

[2] The government assigned Tambon Nong Plong of Mueang Phichit to be part of Wang Sai Phun on 23 September 1993.

[3] Neighboring districts are (from the south clockwise) Thap Khlo, Taphan Hin, Mueang Phichit, Sak Lek of Phichit Province and Noen Maprang of Phitsanulok province.

The district is divided into four sub-districts (tambon), which are further subdivided into 57 villages (muban).