A drive device for a PTO shaft comprising a parking switch to detect a parking state of a vehicle body, a permission switch connected to the parking switch, the permission switch being configured to be switched to permit driving a PTO shaft, the PTO shaft being configured to be driven by a power of a prime mover disposed on the vehicle body; a first switch device to be switched to enable the PTO shaft to be driven when the permission switch is switched to permit driving the PTO shaft under a state where the parking switch detects the parking state of the vehicle body; an on-off switch to switch the driving of the PTO shaft to be turned on and to be turned off; a seat switch to detect an operator seated on an operator seat; and a second switch device connected to an output terminal of the first switch device and to an output terminal of the seat switch, the second switch device being configured to be switched to enable the PTO shaft to be driven based on an input from the output terminal of the first switch device or from the output terminal of the seat switch, wherein a first input terminal of the first switch device is connected to an output terminal of the permission switch, and wherein a second input terminal of the first switch device is connected to an output terminal of the on-off switch, wherein the first switch device is a single stable type, and wherein the permission switch is constituted of a self-returning switch to be operated by being pushed by an operator and is configured to be switched to permit the driving of the PTO shaft when pushed and to be switched not to permit the driving when not pushed. a parking switch to detect a parking state of a vehicle body, a permission switch connected to the parking switch, the permission switch being configured to be switched to permit driving a PTO shaft, the PTO shaft being configured to be driven by a power of a prime mover disposed on the vehicle body; a first switch device to be switched to enable the PTO shaft to be driven when the permission switch is switched to permit driving the PTO shaft under a state where the parking switch detects the parking state of the vehicle body; an on-off switch to switch the driving of the PTO shaft to be turned on and to be turned off; a seat switch to detect an operator seated on an operator seat; and a second switch device connected to an output terminal of the first switch device and to an output terminal of the seat switch, the second switch device being configured to be switched to enable the PTO shaft to be driven based on an input from the output terminal of the first switch device or from the output terminal of the seat switch, wherein a first input terminal of the first switch device is connected to an output terminal of the permission switch, and wherein a second input terminal of the first switch device is connected to an output terminal of the on-off switch, wherein the first switch device is a single stable type, and wherein the permission switch is constituted of a self-returning switch to be operated by being pushed by an operator and is configured to be switched to permit the driving of the PTO shaft when pushed and to be switched not to permit the driving when not pushed.