A mobile apparatus comprising: a main body with a rectangular shape that is capable of being held in a hand and operated with a thumb; a first biosensor located on a first end portion of the mobile apparatus and configured to obtain a first biosignal from a finger or a palm of a first hand holding the mobile apparatus at a first end of the main body; a second biosensor located on the second end portion of the mobile apparatus and configured to obtain a second biosignal from a finger or a palm of a second hand holding the mobile apparatus at a second end of the main body opposite said first end; a touch screen attached to the front surface of the main body and configured to display an operation switch for operation of the mobile apparatus by a thumb; a signal processing unit including at least one signal processor unit configured to process the obtained first and second biosignal, and comprising a switch arrangement changing unit configured to change the arrangement of the operation switch, wherein the switch arrangement changing unit is configured to, when a biosignal is obtained by the first biosensor , change the arrangement of the operation switch in such a manner that the operation switch is arranged along a circular arc of a virtual circle whose center is located at a carpometacarpal joint of the thumb of the second hand holding the mobile apparatus and whose radius is a distance from the carpometacarpal joint to a tip of the thumb, and when a biosignal is obtained by the second biosensor , change the arrangement of the operation switch in such a manner that the operation switch is arranged along a circular arc of a virtual circle whose center is located at a carpometacarpal joint of the thumb of the first hand holding the mobile apparatus. a main body with a rectangular shape that is capable of being held in a hand and operated with a thumb; a first biosensor located on a first end portion of the mobile apparatus and configured to obtain a first biosignal from a finger or a palm of a first hand holding the mobile apparatus at a first end of the main body; a second biosensor located on the second end portion of the mobile apparatus and configured to obtain a second biosignal from a finger or a palm of a second hand holding the mobile apparatus at a second end of the main body opposite said first end; a touch screen attached to the front surface of the main body and configured to display an operation switch for operation of the mobile apparatus by a thumb; a signal processing unit including at least one signal processor unit configured to process the obtained first and second biosignal, and comprising a switch arrangement changing unit configured to change the arrangement of the operation switch, wherein the switch arrangement changing unit is configured to, when a biosignal is obtained by the first biosensor , change the arrangement of the operation switch in such a manner that the operation switch is arranged along a circular arc of a virtual circle whose center is located at a carpometacarpal joint of the thumb of the second hand holding the mobile apparatus and whose radius is a distance from the carpometacarpal joint to a tip of the thumb, and when a biosignal is obtained by the second biosensor , change the arrangement of the operation switch in such a manner that the operation switch is arranged along a circular arc of a virtual circle whose center is located at a carpometacarpal joint of the thumb of the first hand holding the mobile apparatus. <EOS>