He said it could have been stolen for a range of reasons because it was a versatile digger.
Mallard has been working at the cemetery for the past 14 years and the digger, a Bobcat with a smooth, toothless bucket, arrived at the cemetery eight years ago.
It has red hydraulic cables and a flat blade extending from the bucket.
Mallard, who is responsible for digging the graves and looking after the cemetery grounds, said a new digger could cost between $50,000 and $60,000.
"We are missing it, and we would very much like it back."
A Napier City Council spokeswoman said the entrance gate to the cemetery was "severely damaged to gain entry, and the digger was not on a trailer so they would have needed a trailer or truck to remove it".
"It is very disappointing as this digger was dedicated to the cemetery for burials. In the interim council are working around it to make sure there are no disruptions to service."
The council had brought in another digger to cover the work in the interim.
Mallard said although they did have another digger on loan they still occasionally had to do the work by hand.
Police said they received a report of the theft at the Jeffery Drive, Poraiti address.
They are encouraging anyone with information about the vehicle, or those involved in the burglary, to speak with police. Phone 105 and quote file number 200203/2172. Information can also be given anonymously through Crimestoppers on 0800 555 111.
Western Hills cemetery opened in 1985.
The northern crest, topped by a trig point, offers extensive views of farmland and the suburbs of Napier. Before the earthquake of February 3, 1931, the low-lying expanse was covered by the waters and mudflats of the great Ahuriri Lagoon.
The cemetery's lawns were formerly orchards, paddocks and vegetable gardens.
The most recent addition to the cemetery is the SANDS (Still and Newborn Death Support) Memorial, which faces out towards the lagoon.
