A sample transport apparatus comprising: a housing; at least an upper transport line stage accommodated in the housing and including left and right transport lines, each of the left and right transport lines being configured to transport sample holders each capable of holding at least one sample along a side wall of the housing along a long-side direction; a drive mechanism accommodated in the housing, the drive mechanism being configured to transport the sample holders along the left and right transport lines; wires (205 to 209) accommodated in the housing and connected to at least the drive mechanism, wherein the left transport line and the right transport line of the upper transport line stage are arranged in parallel along a long-side side face of the housing; wherein a first distance between the left transport line and the long-side side face that is adjacent the left transport line is shorter than a second distance between the left transport line and the right transport line; and wherein the housing is supported by a base substrate; characterized in that the sample transport apparatus further comprises a lower transport line stage accommodated in the housing below the upper transport line stage and adapted to transport sample holders not holding any samples; a leg that supports the base substrate; and a height adjustment mechanism provided at an attachment portion between the base substrate and posts supporting the lower transport line stage, the height adjustment mechanism being configured to adjust the installation height of the transport lines; wherein a wire accommodating portion is provided in a space below the lower transport line stage, the wire accommodating portion accommodating the wires extracted from a space formed between the left transport line and the right transport line; and wherein the housing has an openable/closable door for exposing the wire accommodating portion to the outside, wherein the openable/closable door forms the long-side side face together with the housing, and is rotatably attached to the base substrate such as to open or close in a vertical direction. a housing; at least an upper transport line stage accommodated in the housing and including left and right transport lines, each of the left and right transport lines being configured to transport sample holders each capable of holding at least one sample along a side wall of the housing along a long-side direction; a drive mechanism accommodated in the housing, the drive mechanism being configured to transport the sample holders along the left and right transport lines; wires (205 to 209) accommodated in the housing and connected to at least the drive mechanism, wherein the left transport line and the right transport line of the upper transport line stage are arranged in parallel along a long-side side face of the housing; wherein a first distance between the left transport line and the long-side side face that is adjacent the left transport line is shorter than a second distance between the left transport line and the right transport line; and wherein the housing is supported by a base substrate; characterized in that the sample transport apparatus further comprises a lower transport line stage accommodated in the housing below the upper transport line stage and adapted to transport sample holders not holding any samples; a leg that supports the base substrate; and a height adjustment mechanism provided at an attachment portion between the base substrate and posts supporting the lower transport line stage, the height adjustment mechanism being configured to adjust the installation height of the transport lines; wherein a wire accommodating portion is provided in a space below the lower transport line stage, the wire accommodating portion accommodating the wires extracted from a space formed between the left transport line and the right transport line; and wherein the housing has an openable/closable door for exposing the wire accommodating portion to the outside, wherein the openable/closable door forms the long-side side face together with the housing, and is rotatably attached to the base substrate such as to open or close in a vertical direction.