To provide a liquid supply system capable of increasing a designing freedom by making a suction one-way valve for permitting only passage of a liquid from the upstream side which becomes an liquid supply source side to the downstream side which becomes a pump side applicable even to a simple structure not required to have high durability, a liquid supply source, and a liquid injection apparatus.

The liquid supply system is provided with an ink cartridge 13 having an ink accommodating part for accommodating ink and an ink delivery part for delivering ink outside, an ink flow path 16 for supplying ink from the upstream side which becomes the ink cartridge 13 side to the downstream, a pump 31 driven by using a part of the ink flow path 16 as a pump chamber, a first one-way valve 38 disposed on the downstream side of the pump chamber of the ink flow path 16 to permit only passage of ink from the upstream side to the downstream side, and a second one-way valve 29 disposed in the ink cartridge 13 to permit only passage of ink from the ink accommodating part side to the ink delivery part side.