“A security incident occurred at Hanover airport around 15h40. A man broke through a barrier in a car which went onto the runway,” Hanover police said on Twitter.
The man, whose car was registered in Poland, was quickly arrested and is being questioned.
Check-in for some flights remained suspended as of 1830 GMT while police investigated.
Part of terminal A was closed but the two other terminals were open, police told German news agency DPA.
Incoming flights were being diverted to other airports.