A sealing device includes a metal ring 110 with a cylindrical section 111 and an inward flange section 112 disposed at one end of the cylindrical section 111. A resin seal 120 has an outer circumference side fixed to the metal ring 110 and an inner circumference side configured to slidably and closely come into contact with an outer circumference surface of the rotary shaft in a state deformed to curve toward a sealing target region. A flat spring 130 includes a plate-shaped annular metal member and has an outer circumference side fixed to the metal ring 110 and an inner circumference side configured to deform to curve along the resin seal 120 and press the inner circumference side of the resin seal 120 radially inward. A metal slide bearing 140, is sandwiched between the resin seal 120 and the inward flange section 112 and configured to slide on the outer circumference surface of the rotary shaft.