The BPM festival was staged between 14 and 18 September in various locales throughout Portimão and Lagoa. The arrests took place at the Arade Congress Centre in Parchal, Lagoa.
A total of 17 men and two women aged 20 to 38 were arrested for crimes including being in possession of drugs and drug trafficking. A further nine people were also arrested for drink-driving.
The BPM Festival showcased over 170 artists and more than 20 events across four days and nights in seven venues in the cities of Portimão and Lagoa.
It was the first time the festival, one of the largest of its kind in the world, has been held in Europe. It is usually held in Mexico.