A housing includes a side wall that includes a button region that receives a pressing operation and a bottom wall that cooperates with the side wall to define a cavity. The bottom wall has first and second regions in which the first region is more easily displaced in response to the pressing operation than the second region. A press sensor is disposed on the bottom wall in the cavity and extends across portions of the first and second regions. A slit is located in the bottom wall between the side wall and the second region and causes the first region to be more easily displaced in response to the pressing operation than the second region.