An electric string instrument that converts a vibration of a string into an electric signal and outputs the electric signal, the electric string instrument comprising: a body on which the string is stretched; and components (15, 24) that are provided in the body and used for outputting the electric signal or playing the electric string instrument, wherein the body has: a component accommodating recessed portion (25, 28) for accommodating the components (15, 24); a cover (26, 30) configured to be attached to the component accommodating recessed portion (25, 28); and a magnetic force generating portion that generates a magnetic force for fixing the cover (26, 30) to the body, the body further includes a cover placement recessed portion in which the cover is disposed and the cover placement recessed portion is provided along an outer circumference of the component accommodating recessed portion, wherein the cover placement recessed portion is constituted by a bottom wall facing a rear surface of the cover and a side wall facing an outer peripheral surface of the cover, the magnetic force generating portion being provided on the bottom wall, and characterised in that the cover placement recessed portion is provided over an entire circumference of the component accommodating recessed portion and the magnetic force generating portion is provided on an entire surface of the bottom wall of the cover placement recessed portion. a body on which the string is stretched; and components (15, 24) that are provided in the body and used for outputting the electric signal or playing the electric string instrument, wherein the body has: a component accommodating recessed portion (25, 28) for accommodating the components (15, 24); a cover (26, 30) configured to be attached to the component accommodating recessed portion (25, 28); and a magnetic force generating portion that generates a magnetic force for fixing the cover (26, 30) to the body, the body further includes a cover placement recessed portion in which the cover is disposed and the cover placement recessed portion is provided along an outer circumference of the component accommodating recessed portion, a component accommodating recessed portion (25, 28) for accommodating the components (15, 24); a cover (26, 30) configured to be attached to the component accommodating recessed portion (25, 28); and a magnetic force generating portion that generates a magnetic force for fixing the cover (26, 30) to the body, the body further includes a cover placement recessed portion in which the cover is disposed and the cover placement recessed portion is provided along an outer circumference of the component accommodating recessed portion, wherein the cover placement recessed portion is constituted by a bottom wall facing a rear surface of the cover and a side wall facing an outer peripheral surface of the cover, the magnetic force generating portion being provided on the bottom wall, and characterised in that the cover placement recessed portion is provided over an entire circumference of the component accommodating recessed portion and the magnetic force generating portion is provided on an entire surface of the bottom wall of the cover placement recessed portion.