A developer supplying system comprising a developer receiving apparatus , and a developer supply container detachably mountable to the developer receiving apparatus , wherein said developer receiving apparatus includes a developer receiving portion for receiving a developer (T); and said developer supply container includes a developer accommodating portion for accommodating a developer (T), and a discharge opening for permitting discharging of the developer (T) from said developer accommodating portion toward said developer receiving portion ; the developer receiving apparatus further includes a filter for permitting venting of said developer receiving portion in and out; and characterized in that said developer supply container further includes a driving force receiving portion , and a pump portion , said pump portion is capable of alternating repeatedly a discharging operation and a suction operation through said discharge opening , and the discharging operation and the suction operation cause air flow out of and into said developer receiving apparatus , said driving force receiving portion is configured to receive a driving force from said developer receiving apparatus , said pump portion is capable of being driven by the driving force received by said driving force receiving portion , and the discharging operation supplies the developer (T) from said developer supply container to said developer receiving portion while discharging the air out of said developer receiving apparatus through said filter and the suction operation sucks the air from said developer receiving apparatus into said developer supply container while sucking the air into said developer receiving apparatus through said filter . said developer receiving apparatus includes a developer receiving portion for receiving a developer (T); and said developer supply container includes a developer accommodating portion for accommodating a developer (T), and a discharge opening for permitting discharging of the developer (T) from said developer accommodating portion toward said developer receiving portion ; the developer receiving apparatus further includes a filter for permitting venting of said developer receiving portion in and out; and characterized in that said developer supply container further includes a driving force receiving portion , and a pump portion , said pump portion is capable of alternating repeatedly a discharging operation and a suction operation through said discharge opening , and the discharging operation and the suction operation cause air flow out of and into said developer receiving apparatus , said driving force receiving portion is configured to receive a driving force from said developer receiving apparatus , said pump portion is capable of being driven by the driving force received by said driving force receiving portion , and the discharging operation supplies the developer (T) from said developer supply container to said developer receiving portion while discharging the air out of said developer receiving apparatus through said filter and the suction operation sucks the air from said developer receiving apparatus into said developer supply container while sucking the air into said developer receiving apparatus through said filter . <EOS>