A working vehicle with a traveling device having wheels, comprising: an electric motor provided on a vehicle body of said working vehicle having wheels (3, 4); an output shaft (17, 61) having an axial base end connected to the electric motor and configured to output rotation of the electric motor; a reduction mechanism which is provided in the vehicle body and configured to reduce rotation of the output shaft (17, 61) to be transmitted to the wheels; a bottomed hole spline with plural hole spline teeth protruding from a hole spline tooth root and formed on the output shaft (17, 61) with an open end on the axial front end side; and an input shaft which has a shaft spline with plural shaft spline teeth spline-coupled to the hole spline and is configured to input the rotation of the output shaft (17, 61) to the reduction mechanism, characterized in that: the output shaft (17, 61) is provided with an oil reservoir space which is formed in an axial innermost part of the hole spline to reserve the lubricant oil, an entire circumference oil path (56, 64A) which is separated axially toward the base end side from the oil reservoir space and is formed over an entire circumference in an outer circumference side of the output shaft (17, 61), and an oil path which provides communication between the oil reservoir space and the entire circumference oil path (56, 64A) and is configured to supply the lubricant oil supplied to the entire circumference oil path (56, 64A) to the oil reservoir space, and an inner diameter dimension of the oil reservoir space is formed to be larger than a tooth root circle diameter of the hole spline to cause the lubricant oil in the oil reservoir space to be supplied into a spline joint gap between the hole spline tooth root and the shaft spline teeth and towards the open end of the output shaft (17, 61) by the rotation of the output shaft (17, 61). an electric motor provided on a vehicle body of said working vehicle having wheels (3, 4); an output shaft (17, 61) having an axial base end connected to the electric motor and configured to output rotation of the electric motor; a reduction mechanism which is provided in the vehicle body and configured to reduce rotation of the output shaft (17, 61) to be transmitted to the wheels; a bottomed hole spline with plural hole spline teeth protruding from a hole spline tooth root and formed on the output shaft (17, 61) with an open end on the axial front end side; and an input shaft which has a shaft spline with plural shaft spline teeth spline-coupled to the hole spline and is configured to input the rotation of the output shaft (17, 61) to the reduction mechanism, characterized in that: the output shaft (17, 61) is provided with an oil reservoir space which is formed in an axial innermost part of the hole spline to reserve the lubricant oil, an entire circumference oil path (56, 64A) which is separated axially toward the base end side from the oil reservoir space and is formed over an entire circumference in an outer circumference side of the output shaft (17, 61), and an oil path which provides communication between the oil reservoir space and the entire circumference oil path (56, 64A) and is configured to supply the lubricant oil supplied to the entire circumference oil path (56, 64A) to the oil reservoir space, and an inner diameter dimension of the oil reservoir space is formed to be larger than a tooth root circle diameter of the hole spline to cause the lubricant oil in the oil reservoir space to be supplied into a spline joint gap between the hole spline tooth root and the shaft spline teeth and towards the open end of the output shaft (17, 61) by the rotation of the output shaft (17, 61). the output shaft (17, 61) is provided with an oil reservoir space which is formed in an axial innermost part of the hole spline to reserve the lubricant oil, an entire circumference oil path (56, 64A) which is separated axially toward the base end side from the oil reservoir space and is formed over an entire circumference in an outer circumference side of the output shaft (17, 61), and an oil path which provides communication between the oil reservoir space and the entire circumference oil path (56, 64A) and is configured to supply the lubricant oil supplied to the entire circumference oil path (56, 64A) to the oil reservoir space, and an inner diameter dimension of the oil reservoir space is formed to be larger than a tooth root circle diameter of the hole spline to cause the lubricant oil in the oil reservoir space to be supplied into a spline joint gap between the hole spline tooth root and the shaft spline teeth and towards the open end of the output shaft (17, 61) by the rotation of the output shaft (17, 61).