A dual-axle hinge structure includes a dual axle assembly, at least one sleeve, and a contactor. The dual axle assembly includes first and second axles that are connected by and mutually push/pull each other through connection members for synchronous rotation. The sleeve is fit over and houses the first and axles. The contactor is arranged between the first and second axles and has two opposite sides respectively in contact engagement with surfaces of the first and second axles. By means of the tight retention achieved with the sleeve and the abutting engagement achieved with the two sides of the contactor, tight engagement is established among the sleeve, the first and second axles, and the contactor to allow for synchronous rotation, in a step-less manner, and positioning of the first axle and the second axle in a tightly retained condition.