A CPAP machine includes a housing, an air pipe, a blower, and a sensor S. The housing includes a first opening and a second opening. The air pipe is disposed in the housing, and has an inlet port continuous with the first opening, and an outlet port. The sensor S measures a temperature or a humidity of a gas that flows through an internal space of the air pipe. The air pipe includes a box that protrudes outward from a wall of the air pipe and a wall disposed in the box. The wall is disposed in the box to define a space continuous with the internal space of the air pipe, a space, and a space that connects the space and the space to each other. The sensor S is disposed at a wall of the box.