Martin is serving a prison term for manslaughter
The advert, for a security system, appeared in Countryside magazine, showing a farmer holding a shotgun.
The drawing has the farmer smiling and giving a thumbs-up sign with the shotgun still smoking and cartridges in mid-ejection.
A member of the public who complained said it was "irresponsible" because it "condoned the use of a shotgun to protect private property".
Farming world
Martin killed one burglar and injured another with a shotgun after they broke into his farmhouse at Emneth Hungate, Norfolk, in August 1999.
He was initially convicted of murder by a jury, but that conviction was reduced to manslaughter by the Court of Appeal last year.
The company behind the campaign is Maxtec Electronix, of Kneesall, Newark, Nottinghamshire.
It said the same advertisement had appeared in magazines targeted at the farming community for six years.
'Dry humour'
It was part of a series reflecting vandalism and theft on farm yards, estates and at pheasant shoots, said the firm.
The cartoon character in the advert represented the client group in the farming community, it said, who are friendly, professional people, who "appreciated the dry humour of the cartoon".
The Advertising Standards Authority (ASA) upheld the complaint, because it implied the farmer had fired the gun against intruders and therefore condoned the use of a shotgun.
The ASA said this was "irresponsible" and asked the advertisers to amend it with the help of the Committee of Advertising Practice Copy Advice team.