A tube connecting apparatus having a first holding assembly and a second holding assembly which are adapted to hold at least two flexible tubes (8, 9) approximately in a parallel state, comprising: a first pressing unit which is provided at the first holding assembly and which is adapted to press the tubes (8, 9) to a flat state; a second pressing unit which is provided at the second holding assembly and which is adapted to press the tubes (8, 9) to a flat state and which is allowed to be located so as to contact the first pressing unit; a supporting member which is adapted to support at least one of the first and second pressing units (6, 7) such that a pressing amount of the at least one of the first and second pressing units (6, 7) to the tubes (8, 9) changes; a cutting unit which is adapted to cut the tubes (8, 9) between the first and second pressing units (6, 7); a first movement unit which is adapted to move at least one of the first and second holding assemblies (2, 3) to change relatively positions of the tubes (8, 9) cut by the cutting unit such that end portions to be connected face each other; and a second movement unit which is adapted to move at least one of the first and second holding assemblies (2, 3) in a direction that the first pressing unit and the second pressing unit separate and a direction that the end portions to be connected of the tubes (8, 9) cut by the cutting unit contact closely each other, characterized in that the first pressing unit has a first engagement portion and the second pressing unit has a second engagement portion, wherein the first engagement portion and the second engagement portion have a first inclined face and a second inclined face which engage each other, and wherein the first inclined face and the second inclined face slidably contact each other while increasing or decreasing engaging force in proportion to a separated distance between the first and second holding assemblies (2, 3) according to driving of the second movement unit, and wherein, when the at least one of the first and second holding assemblies (2, 3) is driven to move in a direction that the holding assemblies (2, 3) separate from each other by the second movement unit, the supporting member is adapted to gradually change the pressing amount of the at least one of the first and second pressing units (6, 7) to the tubes (8, 9) in accordance with a moving amount of the supporting member. a first pressing unit which is provided at the first holding assembly and which is adapted to press the tubes (8, 9) to a flat state; a second pressing unit which is provided at the second holding assembly and which is adapted to press the tubes (8, 9) to a flat state and which is allowed to be located so as to contact the first pressing unit; a supporting member which is adapted to support at least one of the first and second pressing units (6, 7) such that a pressing amount of the at least one of the first and second pressing units (6, 7) to the tubes (8, 9) changes; a cutting unit which is adapted to cut the tubes (8, 9) between the first and second pressing units (6, 7); a first movement unit which is adapted to move at least one of the first and second holding assemblies (2, 3) to change relatively positions of the tubes (8, 9) cut by the cutting unit such that end portions to be connected face each other; and a second movement unit which is adapted to move at least one of the first and second holding assemblies (2, 3) in a direction that the first pressing unit and the second pressing unit separate and a direction that the end portions to be connected of the tubes (8, 9) cut by the cutting unit contact closely each other, characterized in that the first pressing unit has a first engagement portion and the second pressing unit has a second engagement portion,