An operation device for communicating wirelessly with an external information processing apparatus, the operation device being configured to be held by a user with one hand when used, comprising: a main body portion formed in a cylindrical shape as a whole and being incurved toward the center of the main body portion in a longitudinal direction of the main body portion such that the width of the main body portion is smaller in the center of the main body portion than at both end portions (11a, 11b) of the main body portion; a light emitting portion, which is attached at one end portion of the main body portion of the operation device and configured to emit light according to an instruction from the information processing apparatus; a recessed portion formed at a position of the main body portion at which a thumb of the user is placed when the user holds the operation device; and a first button which is disposed at a bottom of the recessed portion and has a top surface adjacent to a rim portion forming a side surface of the recessed portion; and a second button disposed at a position opposite to the first button on a surface of the main body portion of the operation device formed at a position at which an index finger is placed when the user holds the operation device with the user's thumb placed at the position of the recessed portion, wherein the main body portion is sandwiched between the first button and the second button, the end portion at which the light emitting portion is attached has a larger diameter than the light emitting portion in a cross section perpendicular to the longitudinal direction of the main body portion; the second button has such a height that it does not protrude beyond a curved surface connecting the perimeters of the end portions (11a, lib) of the main body portion; the first button is configured to be operated by the user's thumb; and the second button is configured to be operated by the user's index finger. a main body portion formed in a cylindrical shape as a whole and being incurved toward the center of the main body portion in a longitudinal direction of the main body portion such that the width of the main body portion is smaller in the center of the main body portion than at both end portions (11a, 11b) of the main body portion; a light emitting portion, which is attached at one end portion of the main body portion of the operation device and configured to emit light according to an instruction from the information processing apparatus; a recessed portion formed at a position of the main body portion at which a thumb of the user is placed when the user holds the operation device; and a first button which is disposed at a bottom of the recessed portion and has a top surface adjacent to a rim portion forming a side surface of the recessed portion; and a second button disposed at a position opposite to the first button on a surface of the main body portion of the operation device formed at a position at which an index finger is placed when the user holds the operation device with the user's thumb placed at the position of the recessed portion, wherein the main body portion is sandwiched between the first button and the second button, the end portion at which the light emitting portion is attached has a larger diameter than the light emitting portion in a cross section perpendicular to the longitudinal direction of the main body portion; the second button has such a height that it does not protrude beyond a curved surface connecting the perimeters of the end portions (11a, lib) of the main body portion; the first button is configured to be operated by the user's thumb; and the second button is configured to be operated by the user's index finger.