Plaster for fixing drainage tube

A drainage assembly comprising:

• a plaster configured to fix a drainage tube, the plaster including:
• a plurality of support pads attached to a patient's body to be spaced apart from each other, each of the plurality of support pads having a certain thickness,
• a support band fixed to respective upper surfaces of the plurality of support pads to cover a skin, and
• a plurality of holders detachably coupled to an upper surface of the support band to hold and fix the drainage tube;
• and
• the drainage tube configured be inserted into the patient's body and discharge liquid inside the patient's body to an outside of the patient's body, the drainage tube including a flexible tube, a three-way valve, and connectors located on opposite sides with the three-way valve to connect the three-way valve to the flexible tube,
• wherein the support band includes a support that supports the three-way valve and the connectors and separates the three-way valve and the connectors from the skin, and
• wherein restraining protrusions that contact the connectors and prevent movements of the connectors are disposed on both ends of the support, respectively.