The present invention provides an internal combustion engine system. In a system that selects a large-cam as a driving cam at a time of a start of an engine, when an engine stop request is output, itis determined whether there is a small-cam cylinder for which a small-cam is selected as the driving cam. In a case where it is determined that there is a small-cam cylinder, a switching command for switching the driving cam from the small-cam to the large-cam is output. When an engine start request is output, the above determination is performed again. In a case where it is determined that thereis a small-cam cylinder, the switching command is output to all solenoid actuators again. In addition, the drive of the fuel injector is suspended until the switching operation of the driving cam is completed for all cylinders.