A cryocooler which can be installed on an apparatus which includes a stationary portion and a rotating portion which is supported by the stationary portion to be axially rotatable, the cryocooler comprising: a compressor which is installed on the stationary portion when the cryocooler is installed on the apparatus; an expander which is installed on the rotating portion when the cryocooler is installed on the apparatus; and a rotary joint which performs fluid connection between the compressor and the expander, wherein the rotary joint includes, a rotor which is fixed to the rotating portion to be coaxial with a rotation axis of the rotating portion when the cryocooler is installed on the apparatus, a stator which is disposed to be adjacent to the rotor to form a clearance between the rotor and the stator and is fixed to the stationary portion when the cryocooler is installed on the apparatus, a first high pressure flow path which is a flow path for a first high pressure working gas having a first high pressure higher than an ambient pressure of the cryocooler, and extends from the stator to the rotor through the clearance, a second high pressure flow path which is a flow path for a second high pressure working gas having a second high pressure which is higher than the ambient pressure and is lower than the first high pressure, and extends from the rotor to the stator through the clearance, and a working gas seal portion which divides the clearance into a first high pressure section which communicates with the first high pressure flow path, a second high pressure section which is adjacent to the first high pressure section and communicates with the second high pressure flow path, and a pressurization section which is adjacent to the first high pressure section on a side opposite to the second high pressure section, and wherein the pressurization section has an intermediate pressure which is higher than the ambient pressure and is lower than the first high pressure. a compressor which is installed on the stationary portion when the cryocooler is installed on the apparatus; an expander which is installed on the rotating portion when the cryocooler is installed on the apparatus; and a rotary joint which performs fluid connection between the compressor and the expander, wherein the rotary joint includes, a rotor which is fixed to the rotating portion to be coaxial with a rotation axis of the rotating portion when the cryocooler is installed on the apparatus, a stator which is disposed to be adjacent to the rotor to form a clearance between the rotor and the stator and is fixed to the stationary portion when the cryocooler is installed on the apparatus, a first high pressure flow path which is a flow path for a first high pressure working gas having a first high pressure higher than an ambient pressure of the cryocooler, and extends from the stator to the rotor through the clearance, a second high pressure flow path which is a flow path for a second high pressure working gas having a second high pressure which is higher than the ambient pressure and is lower than the first high pressure, and extends from the rotor to the stator through the clearance, and a working gas seal portion which divides the clearance into a first high pressure section which communicates with the first high pressure flow path, a second high pressure section which is adjacent to the first high pressure section and communicates with the second high pressure flow path, and a pressurization section which is adjacent to the first high pressure section on a side opposite to the second high pressure section, and wherein the pressurization section has an intermediate pressure which is higher than the ambient pressure and is lower than the first high pressure.