At 10am on Thursday, there were 26 patients with the virus at the Royal – one of whom is in Critical Care.
This is an increase since last Monday (March 7) when that number was 11.
It comes as the latest official figures show that coronavirus cases are now rising in half of the UK’s council areas.
Krishna Kallianpur, chief nurse at Chesterfield Royal Hospital, said: "We are aware that cases are rising, and we continue to thank our local community for their support in helping us withstand the pressures of COVID-19.
"We remain vigilant and responsive to infection rates and urge anyone coming on site to continue to apply infection prevention measures, such as hand washing, mask wearing and social distancing, and to take up the offer of Covid, and flu, vaccinations to help prevent the spread of infection."
In Chesterfield, numbers rose the fastest in Brookside and Walton in the latest week to March 3.
The ward had 397 Covid-19 cases per 100,000 people, a rise of 18.5 per cent from the previous week.
There were 260,691 positive cases in the UK in the week ending March 3, a two per cent increase on the week before.
Waning effectiveness of boosters, the lifting of many Covid-19 restrictions, and the spread of the highly contagious BA.2 ‘stealth Omicron’ variant have all been touted as potential reasons for rising infection rates.
Staff, visitors, patients and anyone entering the Royal are still expected to wear a surgical face mask and observe social distancing where possible to keep everyone safe.