A portable air cleaner includes a host connected to a mask through a flexible pipe. The host includes a pressurizing and filtering chamber, an elementary air-storing chamber, a secondary air-storing chamber, a jet port and a valve. The pressurizing and filtering chamber includes a pump and a filtering unit placed therein. The elementary air-storing chamber includes a negative ion producer placed therein. The secondary air-storing chamber includes a pressure sensor, a temperature sensor and a temperature-changing element placed therein. The pressurizing and filtering chamber is connected to the elementary air-storing chamber through the jet port. The elementary air-storing chamber is connected to the secondary air-storing chamber through the valve.
