A fluid circulation apparatus, comprising: a first tank to store fluid to be supplied to a fluid ejection head ; a circulation path including a first flow path portion to provide fluid from the first tank to a supply port of the fluid ejection head , and a second flow path portion (31 b) to return fluid from a collection port of the fluid ejection head to the first tank ; the fluid circulation apparatus further comprises: a bypass flow path that connects a primary side of the fluid ejection head and a secondary side of the fluid ejection head in the circulation path in a short circuiting manner; and a buffer tank that is provided in the middle of the bypass flow path , wherein the fluid flowing through the bypass flow path is disposed in a lower region of an accommodation chamber of the buffer tank , and an air chamber is formed in an upper region of the accommodating chamber , the bypass flow path includes a first bypass flow path connecting the buffer tank and the first flow path and a second bypass flow path connecting the buffer tank and the second flow path , and the fluid circulation apparatus further comprises an opening/closing valve connected to the air chamber of the buffer tank and configured to selectively open the air chamber to the atmosphere; characterized in that the first bypass flow path and the second bypass flow path have the same length and the same diameter, the diameter being smaller than the diameter of the circulation path . a first tank to store fluid to be supplied to a fluid ejection head ; a circulation path including a first flow path portion to provide fluid from the first tank to a supply port of the fluid ejection head , and a second flow path portion (31 b) to return fluid from a collection port of the fluid ejection head to the first tank ; the fluid circulation apparatus further comprises: a bypass flow path that connects a primary side of the fluid ejection head and a secondary side of the fluid ejection head in the circulation path in a short circuiting manner; and a buffer tank that is provided in the middle of the bypass flow path , wherein the fluid flowing through the bypass flow path is disposed in a lower region of an accommodation chamber of the buffer tank , and an air chamber is formed in an upper region of the accommodating chamber , the bypass flow path includes a first bypass flow path connecting the buffer tank and the first flow path and a second bypass flow path connecting the buffer tank and the second flow path , and the fluid circulation apparatus further comprises an opening/closing valve connected to the air chamber of the buffer tank and configured to selectively open the air chamber to the atmosphere; characterized in that the first bypass flow path and the second bypass flow path have the same length and the same diameter, the diameter being smaller than the diameter of the circulation path . a bypass flow path that connects a primary side of the fluid ejection head and a secondary side of the fluid ejection head in the circulation path in a short circuiting manner; and a buffer tank that is provided in the middle of the bypass flow path , wherein the fluid flowing through the bypass flow path is disposed in a lower region of an accommodation chamber of the buffer tank , and an air chamber is formed in an upper region of the accommodating chamber , the bypass flow path includes a first bypass flow path connecting the buffer tank and the first flow path and a second bypass flow path connecting the buffer tank and the second flow path , and the fluid circulation apparatus further comprises an opening/closing valve connected to the air chamber of the buffer tank and configured to selectively open the air chamber to the atmosphere; characterized in that the first bypass flow path and the second bypass flow path have the same length and the same diameter, the diameter being smaller than the diameter of the circulation path . <EOS>