Raja led the protest in front of Chennai Central Railway station. Slogans were raised condemning the Land Bill with activists urging the Centre not to proceed with the "anti-farmer" measure.
However, when Left party workers tried to resort to rail roko (stop the train) they were restrained and taken away, police said.
Raja, CPI State Secretary R Mutharasan were among those detained at a Corporation-run Community Hall, police said, adding, they will be released later today.
Party workers staged protests in Kumbakonam, Salem, Dindigul, Virudhunagar, Srivilliputhur, Valliyur, Sankaran Koil and Ambasamudram.