A seal device for a shaft is provided which has a maintenance seal which can reliably seal around the shaft without compression by rotation or pressing force, and which eliminates the necessity of readjustment after replacement of the seal packings. A seal packing is retained in a packing case housed in a casing, and a maintenance seal is housed under the packing case. A pressurizing means resiliently deforms a resilient body fitted so as to form a sealed space. The pressurizing means supplies pressurized fluid into the sealed space and inflates the resilient body to press it against the shaft. The pressurized fluid is discharged after repair of seal packings.