In the shaft sealing device according to one embodiment, a seal ring includes a machine-interior-side seal ring member, and a machine-exterior-side seal ring member. A ring gap is left between the machine-interior-side seal ring member and the machine-exterior-side seal ring member. A seal gap is left between an inner peripheral surface of the machine-interior-side seal ring member and an outer peripheral surface of the rotary shaft and between an inner peripheral surface of the machine-exterior-side seal ring member and the outer peripheral surface of the rotary shaft. The inner peripheral surface of the machine-interior-side seal ring member is a flat surface that generally follows along the outer peripheral surface of the rotary shaft, and a groove extending along a direction of rotation of the rotary shaft is formed in the inner peripheral surface of the machine-exterior-side seal ring member.