An air cleaner (39, 57, 96, 111, 131, 151) for supplying outside air to an internal combustion engine (29, 88), comprising a cleaner container (45, 58, 102, 112, 132, 152) that forms a dirty chamber (51a, 65a, 107a, 117a, 138a, 161a) communicating with outside air and a clean chamber (51b, 65b, 107b, 117b, 138b, 161b) communicating with a supply destination (29, 88) for cleaned air, a cleaner element (49, 63, 105, 115, 136, 158) that is disposed within the cleaner container (45, 58, 102, 112, 132, 152) between the dirty chamber (51a, 65a, 107a, 117a, 138a, 161a) and the clean chamber (51b, 65b, 107b, 117b, 138b, 161b), and a connecting tube (47, 61, 104, 114, 134, 154) that is fixed to the cleaner container (45, 58, 102, 112, 132, 152), opens in a space of the clean chamber (51b, 65b, 107b, 117b, 138b, 161b) via an upstream end within the clean chamber (51b, 65b, 107b, 117b, 138b, 161b), and provides communication between the clean chamber (51b, 65b, 107b, 117b, 138b, 161b) and the supply destination (29, 88), characterised in that a double pipe part (56, 71, 108, 127, 149, 172) is provided at the upstream end of the connecting tube (47, 61, 104, 114, 134, 154), the double pipe part (56, 71, 108, 127, 149, 172) having an outer ring portion (56b, 71b, 108b, 127b, 149b, 172b) surrounding an outer wall face of the connecting tube (47, 61, 104, 114, 134, 154), and a space between the outer ring portion (56b, 71b, 108b, 127b, 149b, 172b) and the connecting tube (47, 61, 104, 114, 134, 154) being separated from a space within the connecting tube (47, 61, 104, 114, 134, 154), whereby the double pipe part (56, 71, 108, 127, 149, 172) comprises a flange portion (56a, 71a, 108a, 127a, 149a, 172a) that spreads outward from an outer wall face of the connecting tube (47, 61, 104, 114, 134, 154), and the outer ring portion (56b, 71b, 108b, 127b, 149b, 172b) that extends from the flange portion (56a, 71a, 108a, 127a, 149a, 172a) toward the upstream end of the connecting tube (47, 61, 104, 114, 134, 154) along the outer wall face while maintaining an interval from the outer wall face. a cleaner container (45, 58, 102, 112, 132, 152) that forms a dirty chamber (51a, 65a, 107a, 117a, 138a, 161a) communicating with outside air and a clean chamber (51b, 65b, 107b, 117b, 138b, 161b) communicating with a supply destination (29, 88) for cleaned air, a cleaner element (49, 63, 105, 115, 136, 158) that is disposed within the cleaner container (45, 58, 102, 112, 132, 152) between the dirty chamber (51a, 65a, 107a, 117a, 138a, 161a) and the clean chamber (51b, 65b, 107b, 117b, 138b, 161b), and a connecting tube (47, 61, 104, 114, 134, 154) that is fixed to the cleaner container (45, 58, 102, 112, 132, 152), opens in a space of the clean chamber (51b, 65b, 107b, 117b, 138b, 161b) via an upstream end within the clean chamber (51b, 65b, 107b, 117b, 138b, 161b), and provides communication between the clean chamber (51b, 65b, 107b, 117b, 138b, 161b) and the supply destination (29, 88), a double pipe part (56, 71, 108, 127, 149, 172) is provided at the upstream end of the connecting tube (47, 61, 104, 114, 134, 154), the double pipe part (56, 71, 108, 127, 149, 172) having an outer ring portion (56b, 71b, 108b, 127b, 149b, 172b) surrounding an outer wall face of the connecting tube (47, 61, 104, 114, 134, 154), and a space between the outer ring portion (56b, 71b, 108b, 127b, 149b, 172b) and the connecting tube (47, 61, 104, 114, 134, 154) being separated from a space within the connecting tube (47, 61, 104, 114, 134, 154), whereby the double pipe part (56, 71, 108, 127, 149, 172) comprises a flange portion (56a, 71a, 108a, 127a, 149a, 172a) that spreads outward from an outer wall face of the connecting tube (47, 61, 104, 114, 134, 154), and the outer ring portion (56b, 71b, 108b, 127b, 149b, 172b) that extends from the flange portion (56a, 71a, 108a, 127a, 149a, 172a) toward the upstream end of the connecting tube (47, 61, 104, 114, 134, 154) along the outer wall face while maintaining an interval from the outer wall face.