Rob Aplin said: "I am fed up with people with poor personal hygiene standards. I have now made it a sackable offence for people to come in without having a shower,- or with dirty underwear."
He has also banned staff from smelling after eating garlic or curry - warning that they need to make sure they brush their teeth - and use perfume and deodorant.
Mr Aplin, who runs a garage in Rockwell Green, sent out an official memo to all employees demanding they adopt good standards of personal hygiene especially in his garage lavatory where hideous smells are left regularly.
The memo warned all employees to make sure they brush their teeth, take showers regularly, flush the staff toilet and change their underpants every day.
He did not say how he would make sure his clean underpants rule was followed but warned it would be enforced.