A tube fixing structure of a bicycle includes a tube (4) constituting the bicycle and a portion (1a) to be fitted into the tube. A space (4a) is formed between the tube and the portion to be filled with a bonding agent (13) and communicates with a bonding agent pouring inlet (11). The space communicates with an air exhaust outlet (12) so as to exhaust air in the space when the bonding agent (13) is poured into the space.