He was born in a small village in Rajshahi district of the then East Bengal, during the British Raj to anti-British activist parents.

Roy, a former member of the Communist Party of India (Marxist), entered politics after being dismissed from his job as chemical engineer in a company for supporting a workers' strike in 1966–1967.

Roy's parents were both anti-British activists also had served time in prison for participation in freedom movement.

He graduated in Science from Surendranath College, Kolkata, and later gained a master's degree in 1959 in Chemical Engineering from the Calcutta University.

After serving there for two years he joined as Research Engineer, and worked under a scientist Dr Kshitish Ranjan Chakraborty in the newly established Projects and Development India Limited at Sindri, Dhanbad.