A clamp apparatus, comprising: a base unit; a first clamp unit having first and second claws (511A, 511B) facing each other in a first axial direction for clamping a work piece at a first clamp position in the first axial direction, first and second driving sources (512A, 512B) linked to the first and second claws (511A, 511B) respectively for moving the first and second claws (511A, 511B) to the first clamp position, and first and second linear guides (513A, 513B) disposed at the base unit for movably supporting the first and second claws (511A, 511B) to the base unit; and a second clamp unit having third and fourth claws (511C, 511D) facing each other in a second axial direction orthogonal to the first axial direction for clamping the work piece at second clamp positions in the second axial direction, third and fourth driving sources (512C, 512D) linked to the third and fourth claws (511C, 511D) respectively for moving the third and fourth claws (511C, 511D) to the second clamp position, and third and fourth linear guides (513C, 513D) disposed at the base unit for movably supporting the third and fourth claws (511C, 511D) to the base unit, wherein a periphery of the base unit has a plurality of protruded pieces (501A, 501B, 501C, 501D) protruding to the first axial direction and the second axial direction, and the first to fourth craws (511A, 511B, 511C, 511D) and the first to fourth linear guides (513A, 513B, 513C, 513D) are disposed at the plurality of the protruded pieces (501A, 501B, 501C, 501D), characterized in that the first to fourth driving sources (512A, 512B, 512C, 512D) are disposed on first surfaces of the first to fourth protruded pieces (501A, 501B, 501C, 501D), respectively, wherein the first to fourth linear guides (513A, 513B, 513C, 513D) are disposed on second surfaces of the first to fourth protruded pieces (501A, 501B, 501C, 501D), respectively, and wherein the first surfaces and the second surfaces are opposite surfaces of the first to fourth protruded pieces (501A, 501B, 501C, 501D). a base unit; a first clamp unit having first and second claws (511A, 511B) facing each other in a first axial direction for clamping a work piece at a first clamp position in the first axial direction, first and second driving sources (512A, 512B) linked to the first and second claws (511A, 511B) respectively for moving the first and second claws (511A, 511B) to the first clamp position, and first and second linear guides (513A, 513B) disposed at the base unit for movably supporting the first and second claws (511A, 511B) to the base unit; and a second clamp unit having third and fourth claws (511C, 511D) facing each other in a second axial direction orthogonal to the first axial direction for clamping the work piece at second clamp positions in the second axial direction, third and fourth driving sources (512C, 512D) linked to the third and fourth claws (511C, 511D) respectively for moving the third and fourth claws (511C, 511D) to the second clamp position, and third and fourth linear guides (513C, 513D) disposed at the base unit for movably supporting the third and fourth claws (511C, 511D) to the base unit, wherein a periphery of the base unit has a plurality of protruded pieces (501A, 501B, 501C, 501D) protruding to the first axial direction and the second axial direction, and the first to fourth craws (511A, 511B, 511C, 511D) and the first to fourth linear guides (513A, 513B, 513C, 513D) are disposed at the plurality of the protruded pieces (501A, 501B, 501C, 501D), characterized in that the first to fourth driving sources (512A, 512B, 512C, 512D) are disposed on first surfaces of the first to fourth protruded pieces (501A, 501B, 501C, 501D), respectively, wherein the first to fourth linear guides (513A, 513B, 513C, 513D) are disposed on second surfaces of the first to fourth protruded pieces (501A, 501B, 501C, 501D), respectively, and wherein the first surfaces and the second surfaces are opposite surfaces of the first to fourth protruded pieces (501A, 501B, 501C, 501D).