A straddled vehicle comprising: a single-cylinder engine including a piston and a crankshaft, the piston provided in a cylinder and moved to-and-fro by combustion of a mixed gas, the crankshaft configured to be rotated along with to-and-fro movement of the piston; a compression release mechanism operable to reduce pressure in the cylinder in a compression stroke of the single-cylinder engine, in a case where the rotation speed of the crankshaft is equal to or less than a pressure-reduction upper limit speed (Ld); a drive wheel configured to receive a rotational force outputted from the single-cylinder engine via the crankshaft and drive the straddled vehicle; a permanent magnet type motor including a rotor and a permanent magnet, the rotor connected to the crankshaft so as to be rotatable in response to rotation of the crankshaft, the permanent magnet provided to the rotor; a battery; an inverter including a plurality of switching parts by which a current flowing between the battery and the permanent magnet type motor is controlled; the straddled vehicle being characterized in that it further comprises a control device configured to control the plurality of switching parts, based on a result of detection performed by a rotor position detection device which is configured to detect the position of the rotor, in such a manner that, upon reception of a start instruction for starting the single-cylinder engine, the permanent magnet type motor applies a force to the piston via the crankshaft such that the rotation speed of the crankshaft in a first combustion cycle coming after the start instruction is equal to or less than the pressure-reduction upper limit speed (Ld) for the compression release mechanism, so that the piston is moved to operate the compression release mechanism in a compression stroke of the first combustion cycle, and then the permanent magnet type motor applies a force to the piston via the crankshaft such that the rotation speed of the crankshaft in a second combustion cycle exceeds the pressure-reduction upper limit speed (Ld) for the compression release mechanism, so that the piston is moved without operating the compression release mechanism, thus assisting compression of the mixed gas in a compression stroke of the second combustion cycle. a single-cylinder engine including a piston and a crankshaft, the piston provided in a cylinder and moved to-and-fro by combustion of a mixed gas, the crankshaft configured to be rotated along with to-and-fro movement of the piston; a compression release mechanism operable to reduce pressure in the cylinder in a compression stroke of the single-cylinder engine, in a case where the rotation speed of the crankshaft is equal to or less than a pressure-reduction upper limit speed (Ld); a drive wheel configured to receive a rotational force outputted from the single-cylinder engine via the crankshaft and drive the straddled vehicle; a permanent magnet type motor including a rotor and a permanent magnet, the rotor connected to the crankshaft so as to be rotatable in response to rotation of the crankshaft, the permanent magnet provided to the rotor; a battery; an inverter including a plurality of switching parts by which a current flowing between the battery and the permanent magnet type motor is controlled; the straddled vehicle being characterized in that it further comprises a control device configured to control the plurality of switching parts, based on a result of detection performed by a rotor position detection device which is configured to detect the position of the rotor, in such a manner that, upon reception of a start instruction for starting the single-cylinder engine, the permanent magnet type motor applies a force to the piston via the crankshaft such that the rotation speed of the crankshaft in a first combustion cycle coming after the start instruction is equal to or less than the pressure-reduction upper limit speed (Ld) for the compression release mechanism, so that the piston is moved to operate the compression release mechanism in a compression stroke of the first combustion cycle, and then the permanent magnet type motor applies a force to the piston via the crankshaft such that the rotation speed of the crankshaft in a second combustion cycle exceeds the pressure-reduction upper limit speed (Ld) for the compression release mechanism, so that the piston is moved without operating the compression release mechanism, thus assisting compression of the mixed gas in a compression stroke of the second combustion cycle.