An image sensor (20A, 200A) that is connected to a data bus to which another image sensor (20B, 200B) is connected and image data is transmitted, and to a collision detection line to which the another image senso: (20B, 200B) is connected and which is pulled up to a voltage at a first level through a pull-up circuit, wherein the image sensor (20A, 200A) is configured to determine, on a basis of a state of the collision detection line, whether a collision of pieces of the image data is to occur on the data bus when the image data is output, and configured to then output the image data to the data bus, the image sensor comprising: an imaging unit configured to perform imaging; and a control unit configured to control output of image data to the data bus, the image data indicating an image depending on imaging, wherein the control unit is configured to: determine whether the collision is to occur based on the state of the collision detection line, allow the image sensor (20A, 200A) to output the image data in a case where it is not determined that the collision is to occur, perform first determination by outputting a voltage in a unique voltage pattern to the collision detection line to determine whether the collision is to occur on a basis of the state of the collision detection line) at a time of output of the voltage in the unique voltage pattern perform second determination in which it is determined whether the state of the collision detection line is not the first level to thereby determine whether the collision is to occur, perform the second determination after the first determination, and perform the second determination in a case where it is not determined that the collision is to occur in the first determination, wherein when the image data is output, a voltage at a second level that is smaller than the voltage at the first level is output to the collision detection line, and wherein the unique voltage pattern is represented by a combination of the first level and the second level. an imaging unit configured to perform imaging; and a control unit configured to control output of image data to the data bus, the image data indicating an image depending on imaging, wherein the control unit is configured to: determine whether the collision is to occur based on the state of the collision detection line, allow the image sensor (20A, 200A) to output the image data in a case where it is not determined that the collision is to occur, perform first determination by outputting a voltage in a unique voltage pattern to the collision detection line to determine whether the collision is to occur on a basis of the state of the collision detection line) at a time of output of the voltage in the unique voltage pattern perform second determination in which it is determined whether the state of the collision detection line is not the first level to thereby determine whether the collision is to occur, perform the second determination after the first determination, and perform the second determination in a case where it is not determined that the collision is to occur in the first determination, wherein when the image data is output, a voltage at a second level that is smaller than the voltage at the first level is output to the collision detection line, and wherein the unique voltage pattern is represented by a combination of the first level and the second level. determine whether the collision is to occur based on the state of the collision detection line, allow the image sensor (20A, 200A) to output the image data in a case where it is not determined that the collision is to occur, perform first determination by outputting a voltage in a unique voltage pattern to the collision detection line to determine whether the collision is to occur on a basis of the state of the collision detection line) at a time of output of the voltage in the unique voltage pattern perform second determination in which it is determined whether the state of the collision detection line is not the first level to thereby determine whether the collision is to occur, perform the second determination after the first determination, and perform the second determination in a case where it is not determined that the collision is to occur in the first determination, wherein when the image data is output, a voltage at a second level that is smaller than the voltage at the first level is output to the collision detection line, and wherein the unique voltage pattern is represented by a combination of the first level and the second level.