An engine device having a blow-by gas returning mechanism that returns a blow-by gas having leaked from a combustion chamber to an intake pipe in which intake air flows, the engine device comprising: a returning hose in which the blow-by gas from the combustion chamber flows; and a blow-by gas mixed joint configured to introduce the blow-by gas flowing in the returning hose to the intake pipe, wherein the blow-by gas mixed joint includes an intake passage disposed on the intake pipe and defining an intake direction, a blow-by gas inlet defining an introduction direction and configured to introduce the blow-by gas into the intake pipe, and a blow-by gas guide plate that guides the blow-by gas introduced from the blow-by gas inlet in the intake passage and that defines an introduction space extending upstream and downstream of the blow-by gas inlet in the intake direction of the intake passage, and in a plane orthogonal to the intake direction of the intake passage, the blow-by gas guide plate is flat and extends across the intake passage and, in a plane parallel with the intake direction of the intake passage, the blow-by gas guide plate closes an upstream end of a part of the introduction space extending upstream of the blow-by gas inlet, and the blow-by gas guide plate comprises a first portion which extends gradually away from an inner wall of the intake passage in a downstream direction, and a second portion which extends parallel to the inner wall of the intake passage in the downstream direction, the second portion extends continuously from the first portion to a predetermined distance in parallel with the intake direction after the first portion, obliquely extending in the intake direction from the inner wall of the intake passage, reaches a predetermined length from the inner wall of the intake passage, and the blow-by gas guide plate is configured to open a downstream end of a part of the introduction space extending downstream of the blow-by gas inlet in the intake passage, and to guide the blow-by gas introduced from the blow-by gas inlet to a predetermined distance so that the blow-by gas is separated from intake air flowing in the intake passage and flows in parallel with the intake air. a returning hose in which the blow-by gas from the combustion chamber flows; and a blow-by gas mixed joint configured to introduce the blow-by gas flowing in the returning hose to the intake pipe, wherein the blow-by gas mixed joint includes an intake passage disposed on the intake pipe and defining an intake direction, a blow-by gas inlet defining an introduction direction and configured to introduce the blow-by gas into the intake pipe, and a blow-by gas guide plate that guides the blow-by gas introduced from the blow-by gas inlet in the intake passage and that defines an introduction space extending upstream and downstream of the blow-by gas inlet in the intake direction of the intake passage, and an intake passage disposed on the intake pipe and defining an intake direction, a blow-by gas inlet defining an introduction direction and configured to introduce the blow-by gas into the intake pipe, and a blow-by gas guide plate that guides the blow-by gas introduced from the blow-by gas inlet in the intake passage and that defines an introduction space extending upstream and downstream of the blow-by gas inlet in the intake direction of the intake passage, and in a plane orthogonal to the intake direction of the intake passage, the blow-by gas guide plate is flat and extends across the intake passage and, in a plane parallel with the intake direction of the intake passage, the blow-by gas guide plate closes an upstream end of a part of the introduction space extending upstream of the blow-by gas inlet, and the blow-by gas guide plate comprises a first portion which extends gradually away from an inner wall of the intake passage in a downstream direction, and a second portion which extends parallel to the inner wall of the intake passage in the downstream direction, the second portion extends continuously from the first portion to a predetermined distance in parallel with the intake direction after the first portion, obliquely extending in the intake direction from the inner wall of the intake passage, reaches a predetermined length from the inner wall of the intake passage, and the blow-by gas guide plate is configured to open a downstream end of a part of the introduction space extending downstream of the blow-by gas inlet in the intake passage, and to guide the blow-by gas introduced from the blow-by gas inlet to a predetermined distance so that the blow-by gas is separated from intake air flowing in the intake passage and flows in parallel with the intake air.