The victims, farmers tending their crops in Brebes district, Central Java, were buried under an avalanche of mud and rock around 8:00 am.
"The landslide buried the farmers working in their rice fields," disaster mitigation agency spokesman Sutopo Purwo Nugroho said in a statement.
The incident followed several days of heavy rain in the mountainous area, about seven hours east of the capital Jakarta.
Another 14 farmers were found with light injuries and have been taken to a nearby medical centre for treatment.
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Residents have been forbidden from entering the area due to fears of further landslides.
"The soil is unstable, if it's raining, it could be dangerous," local sub-district head Apriyanto Sudarmoko told a national TV station.
"We also ask residents living near the site to vacate their homes until it's safe."
Landslides are common in Indonesia, especially during wet season between October and April, when rain lashes the country.
Eight miners were killed on the slopes of Mount Merapi, an active volcano near the city of Jogjakarta, in December last year.