The arrest of the Moroccan, whose name was not revealed, took place in the town of Manresa, north of Barcelona, Xinhua news agency reported.
According to the ministry, the detention means the end of a platform which was "strongly active in spreading the jihad message".
The ministry confirmed the man arrested used several online platforms to "develop a constant and growing work of spreading doctrinal images and also of a strategy of radicalisation common in terrorist groups".
The official communique of the ministry added that the man had displayed an "unstable and violent character" in recent months, "in line with an increase of his commitment to the jihad".
He had also maintained contacts over social networks with someone who had returned from the conflict in Syria and Iraq to "ask for advice and support for his activities".
