After a five-hour preliminary hearing at Bornholm court, the man was remanded in custody for a further four weeks, reports the Ritzau news wire.
He is charged with possession and distribution of explicit child pornography.
The case began two months ago, Bornholm Police deputy inspector Peter Jørgensen confirmed to Ritzau.
Two computers belonging to the man were seized by police from the man's home in the town of Rønne, where he lives with his mother.
The computers were sent to the National Police (Rigspolitiet) cyber crime unit NC3 for further investigation.
“The results of the investigation now show that we are dealing with very coarse child pornography, and he has therefore been arrested,”Jørgensen said during the preliminary hearing on Tuesday, according to Ritzau's report.
Due to the early stage of the investigation, the amount of material discovered by police has not yet been confirmed.
“Investigations are still underway, so I can't say anything about amounts,” Jørgensen said.
The hearing took place behind what is known in the Danish legal system as ‘double-locked doors', meaning that only details of the charge are allowed to be made public.
As such, the means by which the man came under police suspicion also remain unknown.
The plea made by the 18-year-old to the charges also remains unknown, but Jørgensen told Ritzau that the man was considering appealing against his detainment.