A compressor comprising: a casing; a compression mechanism housed in the casing and configured to compress fluid by rotational movement; a rotary drive shaft housed in the casing and connected to the compression mechanism at an upper end part of the rotary drive shaft; a bearing through which the rotary drive shaft penetrates; an oil supply passage formed in the rotary drive shaft to supply lubrication oil to a clearance between the rotary drive shaft and the bearing; and a sealing part configured to reduce or prevent downward oil leakage from the bearing, the compressor further includes a bearing housing which is formed with an insertion hole into which the bearing is inserted and which is fixed to the casing, the rotary drive shaft includes a large-diameter shaft part supported by the bearing, and a small-diameter shaft part connected to a lower end part of the large-diameter shaft part so as to be coaxial to the large-diameter shaft part, the sealing part includes an oil receiving surface which is formed in the bearing housing so as to face a stepped surface formed at a boundary between the large-diameter shaft part and the small-diameter shaft part with a clearance being formed between the oil receiving surface and the stepped surface, and which is formed so as to surround an outer periphery of the small-diameter shaft part, characterised in that the sealing part is formed with a clearance space formed between the stepped surface and the oil receiving surface, and a circular groove formed to surround an outer periphery of the clearance space, a first oil return groove communicating, at one end thereof, with the circular groove and communicating, at the other end thereof, with a predetermined space inside the casing is formed at an inner circumferential surface of the bearing housing defining the insertion hole such that centrifugal force from the rotary drive shaft acts on lubrication oil in the clearance space, the lubrication oil flowing into the clearance space being pushed back to the outside in a radial direction by the centrifugal force. a casing; a compression mechanism housed in the casing and configured to compress fluid by rotational movement; a rotary drive shaft housed in the casing and connected to the compression mechanism at an upper end part of the rotary drive shaft; a bearing through which the rotary drive shaft penetrates; an oil supply passage formed in the rotary drive shaft to supply lubrication oil to a clearance between the rotary drive shaft and the bearing; and a sealing part configured to reduce or prevent downward oil leakage from the bearing, the compressor further includes a bearing housing which is formed with an insertion hole into which the bearing is inserted and which is fixed to the casing, the rotary drive shaft includes a large-diameter shaft part supported by the bearing, and a small-diameter shaft part connected to a lower end part of the large-diameter shaft part so as to be coaxial to the large-diameter shaft part, a large-diameter shaft part supported by the bearing, and a small-diameter shaft part connected to a lower end part of the large-diameter shaft part so as to be coaxial to the large-diameter shaft part, the sealing part includes an oil receiving surface which is formed in the bearing housing so as to face a stepped surface formed at a boundary between the large-diameter shaft part and the small-diameter shaft part with a clearance being formed between the oil receiving surface and the stepped surface, and which is formed so as to surround an outer periphery of the small-diameter shaft part, characterised in that the sealing part is formed with a clearance space formed between the stepped surface and the oil receiving surface, and a circular groove formed to surround an outer periphery of the clearance space, a clearance space formed between the stepped surface and the oil receiving surface, and a circular groove formed to surround an outer periphery of the clearance space, a first oil return groove communicating, at one end thereof, with the circular groove and communicating, at the other end thereof, with a predetermined space inside the casing is formed at an inner circumferential surface of the bearing housing defining the insertion hole such that centrifugal force from the rotary drive shaft acts on lubrication oil in the clearance space, the lubrication oil flowing into the clearance space being pushed back to the outside in a radial direction by the centrifugal force.