A medical tube securing jig includes: a skin securing member having a flange portion and a protruding body； and a medical tube holding mechanism part to hold the medical tube. A recessed portion is formed on the protruding body and has female threads. The medical tube holding mechanism part includes: a sealing member elastically deformed by a pressing force applied to the sealing member when the sealing member engages with the recessed portion by fitting engagement thus being brought into close contact with a side wall surface of the recessed portion, a bottom surface of the recessed portion and the medical tube； and a sealing member pressing body having male threads and configured to apply the pressing force to the sealing member in fastening by making the male and female threads engage, and a slit portion is formed in the sealing member.
