An on-vehicle electronic device comprising: a housing; a panel support unit disposed on a front side of the housing; and a detachable panel having a front portion and a rear portion, the detachable panel including at least one of a control and a display device disposed in the front portion, the detachable panel being detachably attached to the panel support unit, wherein the detachable panel includes a first hook portion and a holding shaft, the first hook portion and the holding shaft being provided in the rear portion of the detachable panel such that the first hook portion and the holding shaft are spaced apart from each other, wherein the panel support unit includes a hook support portion to which the first hook portion is adapted to be hooked, a holding member that is adapted to be moved between a projected position (ii) and a retracted position (i), a spring member that is adapted to urge the holding member toward the projected position, and an operation member operated from outside, wherein a holding recess portion into which the holding shaft is inserted and a temporary support portion that temporarily supports the holding shaft are formed in the holding member, wherein, when the detachable panel is pressed into the panel support unit while being supported at a hook portion where the first hook portion is hooked to the hook support portion, the holding shaft is adapted to be inserted into the holding recess portion, the holding member is adapted to be moved to the retracted position, and the holding member is adapted to be retained by the operation member, thereby the detachable panel becomes stable in an attached posture (iii), and wherein, when the operation member is operated and retention of the holding member is released, the holding member is adapted to be moved to the projected position and the holding shaft is adapted to be temporarily supported by the temporary support portion, and the detachable panel is adapted to be rotated toward the front side about the hook portion where the first hook portion is hooked to the hook support portion and stopped in a temporarily supported posture (iv). a housing; a panel support unit disposed on a front side of the housing; and a detachable panel having a front portion and a rear portion, the detachable panel including at least one of a control and a display device disposed in the front portion, the detachable panel being detachably attached to the panel support unit, wherein the detachable panel includes a first hook portion and a holding shaft, the first hook portion and the holding shaft being provided in the rear portion of the detachable panel such that the first hook portion and the holding shaft are spaced apart from each other, a first hook portion and a holding shaft, the first hook portion and the holding shaft being provided in the rear portion of the detachable panel such that the first hook portion and the holding shaft are spaced apart from each other, wherein the panel support unit includes a hook support portion to which the first hook portion is adapted to be hooked, a holding member that is adapted to be moved between a projected position (ii) and a retracted position (i), a spring member that is adapted to urge the holding member toward the projected position, and an operation member operated from outside, a hook support portion to which the first hook portion is adapted to be hooked, a holding member that is adapted to be moved between a projected position (ii) and a retracted position (i), a spring member that is adapted to urge the holding member toward the projected position, and an operation member operated from outside, wherein a holding recess portion into which the holding shaft is inserted and a temporary support portion that temporarily supports the holding shaft are formed in the holding member, wherein, when the detachable panel is pressed into the panel support unit while being supported at a hook portion where the first hook portion is hooked to the hook support portion, the holding shaft is adapted to be inserted into the holding recess portion, the holding member is adapted to be moved to the retracted position, and the holding member is adapted to be retained by the operation member, thereby the detachable panel becomes stable in an attached posture (iii), and wherein, when the operation member is operated and retention of the holding member is released, the holding member is adapted to be moved to the projected position and the holding shaft is adapted to be temporarily supported by the temporary support portion, and the detachable panel is adapted to be rotated toward the front side about the hook portion where the first hook portion is hooked to the hook support portion and stopped in a temporarily supported posture (iv).