The defibrillator at Dereham Baptist Church is still missing after it was taken between 7pm on Monday July 30 and 7pm on Wednesday August 1.
The machine, usually located at the church on Norwich Street, had been reported to the police as stolen by the church after it was found to have been removed from its box.
Police said that the box was forced open and was still in a lock position.
Minister of the Dereham Baptist Church Nigel Bailey said: 'We haven't heard anything from anybody yet. We've heard reports that it might be safe but we just want it back.
'If someone has it, please bring it back to us.'
The ambulance service are not aware of any incident where the device needed to be used.
The ambulance service also said that it does not own every defibrillator and it's possible that someone took it out to use and hasn't returned it yet.
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