A breath sensor including a main body into which breath can be introduced, a conversion section for converting a gas component contained in the breath to a specific component, and a sensing section for detecting the specific component. The sensing section constitutes a first unit including an integrated detection element and a first heater. The conversion section constitutes a second unit including an integrated catalyst and a second heater. The first unit and the second unit are disposed inside the main body so as to be separated from each other with a gap therebetween, or are in contact with each other via a heat insulating member. The first unit and second unit are in communication with each other through a pipe that allows the breath to pass therethrough, and the pipe is partially bent.
