A laser welding device that joins a plurality of metal members (501, 502, 506, 507, 511, 512, 516, 517, 521, 522, 526, 527, 531, 532) by laser welding, the laser welding device comprising: a laser oscillator that oscillates a laser beam; a light condensing unit that condenses the laser beam on a welding position; a scanning unit that scans a spot of the laser beam; and a control unit that controls the laser oscillator and the scanning unit, wherein while causing the laser oscillator to oscillate the laser beam, the control unit forms a screw portion (101, 106, 111, 116, 121, 126, 131, 141, 146, 151, 156, 166, 171, 176, 181, 186, 201, 206, 211, 216, 221, 225, 231, 235, 241, 246, 251) which is a portion having a dot shape in a plan view and being formed by melting a metal member (501, 502, 506, 507, 511, 512, 516, 517, 521, 522, 526, 527, 531, 532) by spirally scanning the spot of the laser beam so as to circle around a predetermined position, characterized in that while the metal member (501, 502, 506, 507, 511, 512, 516, 517, 521, 522, 526, 527, 531, 532) in the screw portion (101, 106, 111, 116, 121, 126, 131, 141, 146, 151, 156, 168, 173, 176, 181, 186, 201, 206, 211, 216, 221, 225, 231, 235, 241, 246, 251) is in a molten state, the control unit forms a linear portion (102, 107, 112, 117, 118, 127, 132, 134, 136, 142, 147, 148, 152, 157, 159, 167, 172, 177, 182, 187, 190, 195, 202, 207, 212, 217, 222, 232, 233, 242, 243, 247, 248, 252, 253, 254, 255) which is linear in a plan view and continuous with the screw portion (101, 106, 111, 116, 121, 126, 131, 141, 146, 151, 156, 166, 171, 176, 181, 186, 201, 206, 211, 216, 221, 225, 231, 235, 241, 246, 251) and in which a metal member (501, 502, 506, 507, 511, 512, 516, 517, 521, 522, 526, 527, 531, 532) is melted by scanning of the spot of the laser beam so as to be separated from the screw portion (101, 106, 111, 116, 121, 126, 131, 141, 146, 151, 156, 166, 171, 176, 181, 186, 201, 206, 211, 216, 221, 225, 231, 235, 241, 246, 251). a laser oscillator that oscillates a laser beam; a light condensing unit that condenses the laser beam on a welding position; a scanning unit that scans a spot of the laser beam; and a control unit that controls the laser oscillator and the scanning unit, wherein while causing the laser oscillator to oscillate the laser beam, the control unit forms a screw portion (101, 106, 111, 116, 121, 126, 131, 141, 146, 151, 156, 166, 171, 176, 181, 186, 201, 206, 211, 216, 221, 225, 231, 235, 241, 246, 251) which is a portion having a dot shape in a plan view and being formed by melting a metal member (501, 502, 506, 507, 511, 512, 516, 517, 521, 522, 526, 527, 531, 532) by spirally scanning the spot of the laser beam so as to circle around a predetermined position, characterized in that while the metal member (501, 502, 506, 507, 511, 512, 516, 517, 521, 522, 526, 527, 531, 532) in the screw portion (101, 106, 111, 116, 121, 126, 131, 141, 146, 151, 156, 168, 173, 176, 181, 186, 201, 206, 211, 216, 221, 225, 231, 235, 241, 246, 251) is in a molten state, the control unit forms a linear portion (102, 107, 112, 117, 118, 127, 132, 134, 136, 142, 147, 148, 152, 157, 159, 167, 172, 177, 182, 187, 190, 195, 202, 207, 212, 217, 222, 232, 233, 242, 243, 247, 248, 252, 253, 254, 255) which is linear in a plan view and continuous with the screw portion (101, 106, 111, 116, 121, 126, 131, 141, 146, 151, 156, 166, 171, 176, 181, 186, 201, 206, 211, 216, 221, 225, 231, 235, 241, 246, 251) and in which a metal member (501, 502, 506, 507, 511, 512, 516, 517, 521, 522, 526, 527, 531, 532) is melted by scanning of the spot of the laser beam so as to be separated from the screw portion (101, 106, 111, 116, 121, 126, 131, 141, 146, 151, 156, 166, 171, 176, 181, 186, 201, 206, 211, 216, 221, 225, 231, 235, 241, 246, 251).