Grangeway Post Office, which has a counter in McColls newsagents in Grangeway Shopping Precinct, will close on Wednesday, January 8 at 10pm.
A Post Office spokesman said: “The operator for Grangeway Post Office, Rushden has resigned and the premises that we do not own, will be withdrawn for Post Office use tomorrow (January 8 ) at 10pm.
"The shop where the Post Office is based is also closing later this month.
“We apologise for any inconvenience caused by the temporary closure. We understand how important a Post Office is to a community and we are committed to providing a Post Office in the area."
The branch offered mail services as well as Parcelforce Express Services, Foreign Currency, and was an outlet for the National Lottery.
The spokeman added: "We have an interested retailer. Talks are at an early stage.
“In the interim alternative Post Office branches in the area include Rushden and Higham Ferrers.”
Anyone wishing to run the Post Office should click here.