A mass analyzer comprising a sample preparation mechanism for preliminarily preparing an analyzing sample, an interface mechanism for preparing the sample into ions after the required preliminary preparation, an ion trapping part and analyzing part for analyzing the ions, and a controller. The ion trapping part and analyzing part is placed in a box portion of the body, while the interface mechanism is arranged on the front top of the box portion of the body. When the cover at the front top is removed, the front, top and right side of the interface mechanism are opened.