A pipe member is provided that is capable of configuring a heat pipe that can be installed with a high flexibility in accordance with the state of the installation place. A heat pipe configured by using such a pipe member, and a cooling device are also provided. The pipe member includes: an arbitrarily bendable pipe main body whose both ends are closed when used for the heat pipe; a partition wall extended in an axial direction of the pipe main body to partition the inside of the pipe main body into four passages each being utilized as a flow path of the working fluid; and connection paths which allow neighboring passages to communicate with each other out of the four passages.