An engine system comprising: a single-cylinder engine; and a controller (6, 111) configured to control the single-cylinder engine, wherein the single-cylinder engine includes a cylinder, an intake passage arranged to lead air into a combustion chamber of the cylinder, a fuel injection device arranged to inject fuel into the intake passage, an ignition device configured to ignite a fuel-air mixture in the combustion chamber, a first detection subject provided to be rotated together with a crank shaft, and a first detector provided to detect the first detection subject, the controller (6, 111) is configured to be capable of controlling the single-cylinder engine in a normal mode in which ignition of the fuel-air mixture by the ignition device is performed, and an idle stop mode in which the ignition of the fuel-air mixture by the ignition device is not performed, the fuel injection device is controlled to inject fuel in a plurality of cycles right before rotation of the crank shaft is stopped in the idle stop mode, the ignition device is controlled to ignite the fuel-air mixture compressed in a first compression stroke after a change from the idle stop mode to the normal mode based on detection of the first detection subject by the first detector, and the controller (6, 111) is configured to determine a plurality of cycles in which fuel is to be injected to include a last cycle before rotation of the crank shaft is stopped based on a number of cycles until the rotation of the crank shaft is stopped in the idle stop mode that is obtained from a number of times of pre-stop rotation information that relates to a number of times of rotation of the crank shaft in a period from a time when the idle stop mode is started until a time when rotation of the crank shaft is stopped. a single-cylinder engine; and a controller (6, 111) configured to control the single-cylinder engine, the single-cylinder engine includes a cylinder, an intake passage arranged to lead air into a combustion chamber of the cylinder, a fuel injection device arranged to inject fuel into the intake passage, an ignition device configured to ignite a fuel-air mixture in the combustion chamber, a first detection subject provided to be rotated together with a crank shaft, and a first detector provided to detect the first detection subject, a cylinder, an intake passage arranged to lead air into a combustion chamber of the cylinder, a fuel injection device arranged to inject fuel into the intake passage, an ignition device configured to ignite a fuel-air mixture in the combustion chamber, a first detection subject provided to be rotated together with a crank shaft, and a first detector provided to detect the first detection subject, the controller (6, 111) is configured to be capable of controlling the single-cylinder engine in a normal mode in which ignition of the fuel-air mixture by the ignition device is performed, and an idle stop mode in which the ignition of the fuel-air mixture by the ignition device is not performed, the fuel injection device is controlled to inject fuel in a plurality of cycles right before rotation of the crank shaft is stopped in the idle stop mode, the ignition device is controlled to ignite the fuel-air mixture compressed in a first compression stroke after a change from the idle stop mode to the normal mode based on detection of the first detection subject by the first detector, and the controller (6, 111) is configured to determine a plurality of cycles in which fuel is to be injected to include a last cycle before rotation of the crank shaft is stopped based on a number of cycles until the rotation of the crank shaft is stopped in the idle stop mode that is obtained from a number of times of pre-stop rotation information that relates to a number of times of rotation of the crank shaft in a period from a time when the idle stop mode is started until a time when rotation of the crank shaft is stopped.