The farmer who has been named as Jim Keane from Lixnaw is in his 70s and was last seen on Monday.
According to local Gardai, it is understood that the farmer may be missing as a result of a farm accident.
It is believed the farmer may have lost control of his tractor when working in a steep area near a river bank with the tractor found submerged in a tidal river.
A search for the man is being co-ordinated by Gardaí and the Ballybunion Sea Cliff and Rescue Service with locals also joining the search along the river bank.
Members of the public with any information are being asked to contact Listowel Garda station on 06850821