A portable apparatus for monitoring urinary bladder internal pressure includes: a urinary catheter being provided with a pressure measuring sensor and a fixing member for dwelling the pressure measuring sensor in a bladder and being inserted into the bladder to discharge urine and a display device which is connected to the pressure measuring sensor and displays a measured signal measured by the pressure measuring sensor. Since a urinary catheter having a fixing member on which a pressure measuring sensor of a thin-film-type is attached is inserted into a patient and at the same time the pressure of the bladder is monitored in real time by connecting the pressure measuring sensor to a portable display device, urination according to the pressure information of the bladder can be performed in a precise timing.