The accused, identified as Subhash, last night hit his wife Santosh, daughter Sneha (7) and son Himanshu (5) with an axe, killing them on the spot in Sadulpur area, police said.
The incident came to light in the morning when their neighbours spotted the bodies and informed police, they said.
A case has been registered and the accused arrested, they said.
In a separate incident, body of an unidentified woman, aged around 35 years, was recovered today along a roadside on the outskirts of Tonk city, police said.