Deoghar (pronounced Devghar) is a city and a municipal corporation in Deoghar district in the Indian state of Jharkhand. It is also the administrative headquarters of Deoghar district. It is a holy place of Hinduism. The city is primarily known for Baidyanath Temple, one of the 12 Jyotirlingas of Shiva, one of the principal deities in Hinduism. The sacred temples of the city make this a place for pilgrimage and tourists. The city is very sacred to the followers of Hinduism.

The city is administrative headquarter of Deoghar District which comes under Santhal Parganas division of Jharkhand. It is the fifth largest city in Jharkhand and also known as the cultural capital of Jharkhand.

Deoghar is located at 24°29′N 86°42′E / 24.48°N 86.7°E / 24.48; 86.7. It has an average elevation of 255 metres (833 feet). It is a part of the Indian peninsular plateau which forms a part of the oldest landmass on Earth, Gondwana land. Deoghar is situated on the bank of Ajay river (which originates from Batpar village of Jamui district in Bihar) and its tributary Dadhawa river (which originates from Purnia Lake near Karangarh village 24°35′44″N 86°28′28″E / 24.595501°N 86.474369°E / 24.595501; 86.474369 in Jamui district of Bihar). The city is surrounded with various small relict hills such as Dighriya Pahaad, Nandan Pahaad, Trikuti Pahaad, and Tapovan Pahaad. Dighriya Pahaad forms the western boundary of the city and there is a national park being constructed on these hills. Nandan Pahaad is a children's amusement place and serves as one of the principal recreational places in the city. Tapovan Pahaad has its cultural relevance found in Hindu scriptures. It is one of the amusement places in the city and serves as a habitat for monkeys.

Deoghar has an area of 119 square kilometres (46 sq mi).

According to the 2011 Census of India, Deoghar had a total population of 203,123, of which 107,997 (53%) were males and 95,126 (47%) were females. Population in the age range 0–6 years was 26,893 (13%). The total number of literate persons in Deoghar was 150,988 out of which 85,439 are males while 65,549 are females. Average literacy rate of Deoghar city is 85.68 percent of which male and female literacy was 91.24 and 79.37 percent respectively.

Hinduism is the prominent religion in Deoghar followed by 94.30% of the population. Christianity is second most followed religion in the district by 2.65% of the people. Minorities are Muslims 2.23%, Jainism by 0.07%, Sikhism by 0.03% and Buddhism by 0.03%. Around 0.04% stated other religion and approximately 0.04% stated 'no particular religion.

The Economy of Deoghar is largely dependent on religious tourism and hospitality. Deoghar is the fifth largest city in the state of Jharkhand.

Industry in Deoghar is mainly based on IT, agriculture, hospitality, petroleum, tourism, and in the service sector. Hotels like Amrapali Clarks Inn (a collab of Amrapali Groups & Clarks Inn Group of Hotels), Hotel Imperial Heights, etc. are renowned groups of hospitality industry here. Various small and middle scale industries are present in Deoghar - HIL Ltd, MR Real Food, Shree Guru Agrotech, PDRD Rice Mill, Tulsi Agro Foods. Some large industrial projects are also present: