A pressure adjusting mechanism for adjusting pressure applied on a thermal print head includes a pressing plate, a plurality of resilient members and a pressure adjusting member. The pressing plate is disposed above the thermal print head and comprising a first pressed section and a second pressed section connected to the first pressed section. The plurality of resilient members is connected to the first pressed section of the pressing plate and the thermal print head and to the second pressed section of the pressing plate and the thermal print head, respectively. The pressure adjusting member is pivoted to the pressing plate for driving the pressing plate to move relative to the thermal print head, so as to press the plurality of resilient members for providing the thermal print head with pressure, such that the plurality of resilient members drives the pressing plate to equilibrate the pressing plate.