Countdown says staff and shoppers need to wear masks in its stores, but it will leave the enforcement to police.
From today, staff and customers must wear masks at essential services, such as supermarkets, pharmacies, dairies and service stations.
New Zealanders must also wear masks at bus terminals and in taxis.
Countdown told RNZ it understood some people couldn't wear masks - including those under 12, people with speech impediments and others who might have a medical reason or medical certificate. People in those situations should tell staff, according to advice on its website.