The protestors were demonstrating against the alleged government apathy towards the state's farming sector.
Carrying posters and banners and raising anti-government slogans, the activists under the banner of Nava Nirman Krushak Sangha (NNKS) held the demonstration in the prohibited area close to Naveen Nivas, the chief minister's residence, police said.
"Police have detained 55 demonstrators," Assistant Commissioner of Police Pranadhan Mohapatra told IANS.
"The government has been neglecting farmers. Farmers should be provided adequate amount of support price for their produces, security pension and other benefits," NNKS leader Akshay Kumar said.
State Energy and Information and Public Relation Minister Arun Kumar Sahu said the activists staged the demonstration in the prohibited area without taking permission from the local administration or police.