Ratu is a community development block in the Ranchi Sadar subdivision of Ranchi district, in the Indian state of Jharkhand. Ratu fort, located in Ratu, is a fort of Nagvanshi royal family.

Ratu is located at 23°25′N 85°12′E / 23.41°N 85.2°E / 23.41; 85.2.

Ratu CD block is located on the Ranchi plateau proper. It has an average elevation of 2,140 feet (650 m) above mean sea level and the land is undulating.

Ratu CD block is bounded by the Burmu CD block on the north, Kanke CD block on the west, Nagri and Itki CD blocks on the south and Mandar CD block on the west.

Ratu CD block has an area of 104.47 km².Ratu police station serves Ratu CD block. The headquarters of Ratu CD block is located at Ratu town.

According to the 2011 Census of India, Ratu CD block had a total population of 76,565, of which 54,186 were rural and 22,379 were urban. There were 38,785 (51%) males and 37,780 (49%) females. Population in the age range 0–6 years was 10,935. Scheduled Castes numbered 2,609 (3.41%) and Scheduled Tribes numbered 34,676 (45.29%). The tribe of this block is the Kurukh.

The only census town in Ratu CD block is (2011 population figure in brackets): Ratu (22,379).

Large villages (with 4,000+ population) in Ratu CD block are (2011 census figures in brackets): Tigra (4,713), Nagri (6,118) and Gutuwa (4,835).