A mass flow controller includes a base having a first passage, an inlet portion for introducing fluid into the first passage, an outlet portion for releasing the fluid from the first passage, and a second passage branched from a first upstream portion of the first passage and connected to a second downstream portion of the first passage A mass flow sensor is connected to the first passage between the inlet portion of the base and the first portion of the first passage; A first valve is disposed in-line with the first passage between the first and second portions. The first valve controls the mass flow of the fluid passing through the first passage;. A second valve is disposed in-line with the second passage to opens/close the second passage. A valve controller compares the mass flow measured by the mass flow sensor to a standard flow, and then positions the first valve such that the measured mass flow corresponds to the standard flow.