A touch input system has an operation input device having a sensor and a CPU. The CPU is configured to display a mark as a selection object on a display based on a first touch operation. The CPU is further configured to determine an operation mode of a series of touch operations including the first touch operation and the second touch operation. In determining, the CPU is configured to classify the touch operations into any of groups of first touch operations and second touch operations based on a time difference between the touch operations detected.