A mobile device which senses particulate matter is provided. The mobile device includes a housing having an air flow path through which air flows when the mobile device is shaken; an inertia sensor that detects acceleration of the mobile device; a light-scattering type sensor that irradiates the air flow path with light and detects particulate matter in air flowing through the air flow path; and a controller that includes a counter for counting the particulate matter detected by the light-scattering type sensor, and a flow rate calculator for detecting an air flow rate of the air flow path based on a detection signal of the inertia sensor.