The boarding school says the staff member has been suspended pending the outcome of the investigation into alleged assaults on a teenage girl.
The allegations involve a school in Sussex and date back up to 26 years ago.
The £11,000-a-term Shrewsbury School, based in Kingsland, has released a statement confirming one of its staff was being questioned by police about the allegations.
It follows the arrest of a man in Shrewsbury by West Mercia Police officers yesterday. Police spokesman Paul Roberts said the arrest was on suspicion of sexual assaults at an address in West Sussex.
He said: "He remains in police custody at this time. West Mercia Police are assisting Sussex Police with their investigation."
Sussex Police spokesman Tim Mahony said: "Two men were arrested at addresses in Shropshire and North Yorkshire on suspicion of rape and other sexual assaults on a teenage girl in West Sussex during the late 1980s and early 1990s.
"They are currently in custody at police stations near where they live, for interview and further inquiries.
"The investigation is being carried out by specialist child safeguarding detectives from Sussex Police."
A statement from the school said: "Shrewsbury School understands that a police investigation into events at a school in Sussex over 10 years ago involves a member of the current staff at the school.
"The school is co-operating fully with the relevant authorities and the individual has been suspended from duties pending the outcome of any investigation. At present, there is no indication that the investigation involves any activity during the individual's employment at Shrewsbury School.
"There is no suggestion that pupils at the school have been put at risk or harmed in any way.
"Nevertheless, the school is committed to taking all necessary measures to protect pupil welfare and is taking a number of steps to support pupils who may be concerned and to minimise any disruption caused by the suspension.
"Due to the nature of the investigation, the school is unable to comment further at this time."