A door panel of a side door of a machine has a latching mechanism, and a frame of the machine includes a striker. The striker includes a pair of vertically arranged mounting base portions, a pair of slanted shimmy-stopping surface portions formed on the mounting base portions so as to protrude in a V-like shape towards the latching mechanism, and a metal hooking portion protruding from a flat end portion that is provided between the slanted shimmy-stopping surface portions. The latching mechanism includes a mechanism body portion including main body plates. A U-shaped latch groove portion for engaging the metal hooking portion of the striker is formed by cutting away a part of each main body plate, and shimmy suppressing portions that are vertically arranged in a V-like shape are provided at the open end of each latch groove portion.