an expanded view illustrating a side cross sectional structure of a second exhaust pathway 220 and a toilet 10 of a bathroom ventilation system according to an embodiment of the present invention as shown in fig1 to 5 according to an embodiment of the present invention the bathroom ventilation system includes an external air traveling tube 100 an internal air traveling tube 200 a bi directional ventilation tube 300 an intake adjusting member 400 and an air purifying filter 500 the external air traveling tube 100 is shaped as a hollow tube including a pathway through which air may flow the external air traveling tube 100 is provided at an upper side of a bathroom ceiling panel the external air traveling tube 100 is connected with an air intake fan 150 that takes air in from the outside and moves the taken in air to the inside of the bathroom here the external air traveling tube 100 is preferably formed of a flexible hose for allowing the external air traveling tube 100 to be freely adjusted in shape and arrangement upon installation the air intake fan 150 has the same structure as that of a typical blower and detailed description thereof is skipped further the air purifying filter 500 to be described below is provided in a middle section of the external.