The decision to put a parking ticket on a bus during a layover at a stop has been called "absolutely ridiculous".
The driver of the 44 service was issued the ticket in Market Harborough, Leicestershire, on Monday morning.
Centrebus operations manager Mick Rossiter said it was "a slap in the face" for drivers who continued to work throughout lockdown.
Leicestershire County Council said the notice "was issued as the bus appeared to be parked up and unattended".
Mr Rossiter said Centrebus had operated the 44 route from Foxton to Fleckney on behalf of the county council for several years.
As part of the council timetable, the service requires a 20-minute layover in Market Harborough before resuming the service.
"It's quite bizarre," he said.
"The driver is out all day, and takes his breaks on the road, he went across the road during the layover to get a sandwich and a drink.
"Six minutes later a traffic warden had slapped the fine on the bus."
He added: "It's completely unfair."
The £70 penalty charge notice was issued for stopping on a restricted bus stop or stand.
Centrebus is appealing against the ticket.
The council spokeswoman said: "As a council, we only deal with a small number of this type of offence and the work done by our enforcement officers is important in deterring drivers from parking inappropriately as we look to keep our roads and streets safe and traffic on the move."
She added the appeal would be "carefully considered".