An excavator, the excavator comprising: a turning drive unit, the turning drive unit including a turning electric motor; a turning speed reducer configured to transmit a rotational driving force of the turning electric motor to a turnable body the turning speed reducer including an output shaft; a brake unit configured to maintain the turnable body in a state where turning of the turnable body is stopped; a casing forming a space in which the turning speed reducer and the brake unit are lubricated with lubricant oil and accommodated; characterized in that: the output shaft includes a relief portion (46a2C) and a spline formation portion (46a2L) on which splines are formed, the spline formation portion (46a2L) extending from the relief portion (46a2C) in an axial direction of the output shaft, the relief portion (46a2C) formed at a time of forming the splines and decreasing in diameter toward the spline formation portion (46a2L); the turning drive unit further including: a collar fixed around the output shaft so as to rotate with the output shaft, the collar covering at least a part of the relief portion (46a2C); and a sealing member provided between the collar and the casing, the sealing member hermetically sealing the lubricant oil inside the space. a turning drive unit, the turning drive unit including a turning electric motor; a turning speed reducer configured to transmit a rotational driving force of the turning electric motor to a turnable body the turning speed reducer including an output shaft; a brake unit configured to maintain the turnable body in a state where turning of the turnable body is stopped; a casing forming a space in which the turning speed reducer and the brake unit are lubricated with lubricant oil and accommodated; a turning electric motor; a turning speed reducer configured to transmit a rotational driving force of the turning electric motor to a turnable body the turning speed reducer including an output shaft; a brake unit configured to maintain the turnable body in a state where turning of the turnable body is stopped; a casing forming a space in which the turning speed reducer and the brake unit are lubricated with lubricant oil and accommodated; characterized in that: the output shaft includes a relief portion (46a2C) and a spline formation portion (46a2L) on which splines are formed, the spline formation portion (46a2L) extending from the relief portion (46a2C) in an axial direction of the output shaft, the relief portion (46a2C) formed at a time of forming the splines and decreasing in diameter toward the spline formation portion (46a2L); the turning drive unit further including: a collar fixed around the output shaft so as to rotate with the output shaft, the collar covering at least a part of the relief portion (46a2C); and a sealing member provided between the collar and the casing, the sealing member hermetically sealing the lubricant oil inside the space. a collar fixed around the output shaft so as to rotate with the output shaft, the collar covering at least a part of the relief portion (46a2C); and a sealing member provided between the collar and the casing, the sealing member hermetically sealing the lubricant oil inside the space.