Siwan community development block or simply Siwan Block (Hindi: सिवान सामुदायिक विकास खण्ड) is a Community development block in district of Siwan in Bihar state of India.

The total area of Siwan Block is 137.34 square kilometres (53.03 sq mi) and total population of block is 340,983 (including rural area and urban city).

[1] Siwan Nagar Parishad is the headquarter of the block.

Siwan block is divided into many Panchayats and a Municipality.

[2] There are many Gram Panchayats in Siwan block:[3]