A machine tool system for transporting tools and workpieces to a plurality of machine tools (11, 31), the system comprising: a plurality of machine tools (11, 31), wherein at least one of the plurality of machine tools (11, 31) has a pallet chuck for engagement with a pallet, a plurality of tool holders each configured for holding a tool, 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 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 are mounted are stored in a state in which each workpiece 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 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 is transported from the workpiece storage to one of the plurality of machine tools (11, 31), the self-propelled robot transports the workpiece by gripping the second groove-like engagement part of the workpiece adapter. a plurality of machine tools (11, 31), wherein at least one of the plurality of machine tools (11, 31) has a pallet chuck for engagement with a pallet, a plurality of tool holders each configured for holding a tool, 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 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 are mounted are stored in a state in which each workpiece 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 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 is transported from the workpiece storage to one of the plurality of machine tools (11, 31), the self-propelled robot transports the workpiece by gripping the second groove-like engagement part of the workpiece adapter.