Gwanaksan (Korean: 관악산) is a mountain in southern Seoul, South Korea.

The name gwanak means "hat-shaped peak," and refers to its gat-like profile.

Also nearby is the Anyang Resort Area, a popular local tourist attraction.

On the mountain itself lie numerous Buddhist temples, including Wongaksa.

The mountain is very popular with older climbers, since it can easily be reached by Seoul's public transportation.