Police uniforms, handcuffs and batons are among equipment stolen from the Te Awamutu Police Station, in Waikato.
Police said the burglary happened on Tuesday, and the items might have been stolen by someone wanting to impersonate a police officer.
They were asking people who were approached by an officer in the area to establish their identity if they had any doubts.
Stab-resistant body armour and pepper spray was also taken from the station.
Impersonating a police officer is a crime and carries a maximum penalty of 12 months in prison and a fine of $15,000.
Police said an officer's personal car was also damaged on Wednesday, and the burglary was one of a series in Te Awamutu this week.