A machine tool system for transporting tools (T) and workpieces (W) to a plurality of machine tools , the system comprising: a plurality of machine tools , wherein at least one of the plurality of machine tools has a pallet chuck for engagement with a pallet , a plurality of tool holders each configured for holding a tool (T), a self-propelled robot having a hand comprising two fingers for engagement with a predetermined shape, a plurality of tool holder adapters each having a hole for accommodating one of the respective tool holders and a flange having formed therein a first groove-like engagement part for engagement with the fingers of the hand , a tool storage for storing the plurality of tool holder adapters , a plurality of pallets configured to engage with the at least one pallet chuck ; a plurality of workpiece adapters each including an attachment part to which a workpiece (W) can be attached and a second groove-like engagement part for engagement with the fingers of the hand , said second groove-like engagement part being formed in an outer circumference of the workpiece adapter between the pallet and the attachment part , and a workpiece storage in which the plurality of pallets to which workpieces (W) are mounted are stored in a state in which each workpiece (W) is attached to a respective one of the attachment parts , wherein the system is configured such that, when one of the plurality of tool holders is transported from the tool storage to one of the plurality of machine tools , the self-propelled robot transports the tool (T) by gripping the first groove-like engagement part of the tool holder adapter , and wherein the system is configured such that, when one of the respective workpieces (W) is transported from the workpiece storage to one of the plurality of machine tools , the self-propelled robot transports the workpiece (W) by gripping the second groove-like engagement part of the workpiece adapter . a plurality of machine tools , wherein at least one of the plurality of machine tools has a pallet chuck for engagement with a pallet , a plurality of tool holders each configured for holding a tool (T), a self-propelled robot having a hand comprising two fingers for engagement with a predetermined shape, a plurality of tool holder adapters each having a hole for accommodating one of the respective tool holders and a flange having formed therein a first groove-like engagement part for engagement with the fingers of the hand , a tool storage for storing the plurality of tool holder adapters , a plurality of pallets configured to engage with the at least one pallet chuck ; a plurality of workpiece adapters each including an attachment part to which a workpiece (W) can be attached and a second groove-like engagement part for engagement with the fingers of the hand , said second groove-like engagement part being formed in an outer circumference of the workpiece adapter between the pallet and the attachment part , and a workpiece storage in which the plurality of pallets to which workpieces (W) are mounted are stored in a state in which each workpiece (W) is attached to a respective one of the attachment parts , wherein the system is configured such that, when one of the plurality of tool holders is transported from the tool storage to one of the plurality of machine tools , the self-propelled robot transports the tool (T) by gripping the first groove-like engagement part of the tool holder adapter , and wherein the system is configured such that, when one of the respective workpieces (W) is transported from the workpiece storage to one of the plurality of machine tools , the self-propelled robot transports the workpiece (W) by gripping the second groove-like engagement part of the workpiece adapter . <EOS>