To provide an atmospheric pressure detecting device capable of reducing the number of atmospheric pressure sensors, without reducing detecting accuracy.

This atmospheric pressure detecting device has the atmospheric pressure sensors 30 having a detecting body 31 detecting atmospheric pressure, a switching means 20 switching to an intake air introducing state of communicating the atmospheric pressure sensors 30 with suction air and an atmosphere introducing state of communicating the atmospheric pressure sensors 30 with the atmosphere, and an ECU 40 as an electronic control device for controlling switching operation of the switching means 20 in response to an operation state of an engine.