Warning letters offering advice have been distributed to parents and carers at Telford Priory School after it confirmed the virus was circulating among some of the school's 900 pupils.
The secondary school, on New Road in Wrockwardine Wood, said it is mitigating the outbreak by conducting more frequent cleans and advising affected students to stay at home.
Symptoms include diarrhoea and vomiting which usually last up to 48 hours.
The letter, from deputy headteacher Sarah Murdoch, is advising parents and carers to keep students away from large gatherings and vulnerable people.
It reads: "We are following advice from Public Health England (PHE) West Midlands on managing the outbreak, including increasing cleaning throughout the school.
"We would be very grateful for the support of parents in helping us reduce the spread of the infection.
"If your child has symptoms of diarrhoea and or vomiting, please keep them at home until 48 hours after they are symptom free.
"During this time, they should not mix with other children outside the home or visit local venues."
It adds: "Hand washing is one of the most important ways to prevent the spread of these infections.
"Please keep your child away from other children and people that are particularly vulnerable, eg the elderly and those with chronic illnesses."
Norovirus is commonly known as the winter vomiting disease and often occurs in communities, schools and nurseries in the winter months.