Jakub Skrzypski was arrested in August after he was accused of plotting to sell arms to the West Papua Liberation Army.
His lawyer, Latifah Anum Siregar, says Mr Skrzypski was sentenced on Thursday to five years imprisonment by judges at Wamena City Court.
His co-defendant, Papuan student Simon Magal, was jailed for four years for allegedly communicating with Mr Skrzypski.
Prosecutors had sought a 10-year sentence for both men.
Ms Siregar says she will appeal the decision at a Papuan High Court.
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