The discovery comes just days after an unmanned aircraft went down in Croatia.
Romanian prosecutors say they have launched a criminal probe after an “unmanned aircraft” was spotted in the northern county of Bistrita-Nasaud.
“So far, the origin of the aircraft has not been established, and its owner has not been identified,” prosecutors in Cluj County said.
“An investigation is underway to determine the circumstances in which the aircraft was flown and to identify the pilot of the aircraft.”
The drone-type aircraft was discovered by a young man in a field near his house, Bistrita County police stated.
The drone has since been identified as an Orlan-10, which is used in groups of up to five for tasks ranging from gathering intelligence to electronic warfare and pinpointing targets for artillery and aircraft strikes.
The drone bore no markings or an identification number. Russia is the only known operator of this type of unmanned aircraft.
It comes days after a Russian-made unmanned aircraft crossed Romania and Hungary before entering Croatia and crashed late on Thursday.
The drone went down in a Zagreb field, 50 metres from a large university dormitory. Around 40 cars were damaged in the incident but no injuries have been reported.
Croatian defence minister Mario Banožić said on Sunday that the aircraft contained "aeroplane bomb parts".
"Traces of explosives were found, as well as other traces that indicate that this was not a scouting aircraft," he said.
Banožić said that the drone could have been operated by either Ukrainian forces or the Russian military.
Croatian officials have criticised NATO for reacting slowly to a military drone that flew over several member states for at least an hour.
"We cannot tolerate this situation, nor should it have ever happened," Prime Minister Andrej Plenković said while visiting the crash site on Saturday.
NATO said the alliance's integrated air and missile defence had tracked the object.