Summary: We introduce a computer tool called Knot2000 (K2K) which was developed for the purpose of supporting research in knot theory. K2K is a package on Mathematica which consists of 19 functions and it has already been opened to the public with other external programs and data files. In this paper, we will describe, focusing on the usage of each function and some examples, effective ways to use K2K, and show its availability.