He was 86 and leaves behind wife Radha, daughter of celebrated poet G Sankara Kurup and three daughters.
Condoling his death, Chief Minister Pinarayi Vijayan said Achuthan's contribution to Malayalam literature was 'priceless'.
His passing away was a great loss to Malayalam literature, vijayan said in a message.
His works include 'Swathanthrya Samaravum Malayala Sahithyavum', 'Paschathya Sahitya Darshanam', 'Cherukadha Innale Innu' among others.
Prof Achuthan won the Sahitiya Akademi award in 1976.