The present invention provides a program analysis program, a program analysis device, and a program analysis method which can analyze programs and obtain input/output information of the programs effectively. The program analysis device includes an execution path detection unit that detects an execution path and a variable from a group of programs, an execution path pursuit unit that pursues the detected execution path and variable, a variable value limitation unit that seeks values that the variable can turn out to be along with the pursuit for execution path, and limits the variable value in the execution path to be pursued afterward, an execution path limitation unit that, in case there arises a point at which the execution path branches depending on a condition that the variable value satisfies in the pursuit for execution path, after the branch point, limits the pursued execution path only to an execution path in which the limited variable value satisfies the condition, and an input/output information acquisition unit that, in case there arises a point at which data is input or output in the pursuit for execution path, acquires the input/output information.