A fixing device (10, 40) suitable for fixing an electronic component comprising: a heat radiation member (11, 41) having a top surface, said top surface including a central attaching surface (11b, 41b) and a lateral contacting surface (11c, 41c) separated by an engaging groove (11a, 41a), the central attaching surface (11b, 41b) being higher than the lateral contacting surface (11c, 41c); an insulation member (13, 43) having an accommodation portion (13b, 43b) for the electronic component, the electronic component to be sandwiched between the heat radiation member (11, 41) and said insulation member (13, 43); a position determining means for determining a position of the electronic component relative to the heat radiation member (11, 41), said position determining means including a position determining pin (21c, 51c) convexly provided at one of the heat radiation member (11, 41) and the insulation member (13, 43) and configured to penetrate through a part of the electronic component, said position determining means further including a position determining concave portion (11d, 41d) concavely provided at the other of the heat radiation member (11, 41) and the insulation member (13, 43) and configured to be fitted with the position determining pin (21c, 51c); a biasing member (14, 44) suitable for holding the heat radiation member (11, 41) and the insulation member (13, 43) along with the electronic component by elastically contacting a first end (22, 52) and a second end (23, 53) thereof with the engaging groove (11a, 41a) and the insulation member (13, 43), respectively and by contacting a portion of said biasing member (14, 44) situated between said first end and said second end with the lateral contacting surface (11c, 41c) of the heat radiation member (11, 41); wherein the central attaching surface (11b, 41b) of the heat radiation member (11, 41) is configured to be attached with an external heat radiation member; and wherein the biasing member (14, 44) includes a biasing portion (24, 55) which projects above the central attaching surface (11b, 41b) when the electronic component is fixed in its final position by said biasing member (14, 44), said biasing portion being configured to elastically contact said external heat radiation member. a heat radiation member (11, 41) having a top surface, said top surface including a central attaching surface (11b, 41b) and a lateral contacting surface (11c, 41c) separated by an engaging groove (11a, 41a), the central attaching surface (11b, 41b) being higher than the lateral contacting surface (11c, 41c); an insulation member (13, 43) having an accommodation portion (13b, 43b) for the electronic component, the electronic component to be sandwiched between the heat radiation member (11, 41) and said insulation member (13, 43); a position determining means for determining a position of the electronic component relative to the heat radiation member (11, 41), said position determining means including a position determining pin (21c, 51c) convexly provided at one of the heat radiation member (11, 41) and the insulation member (13, 43) and configured to penetrate through a part of the electronic component, said position determining means further including a position determining concave portion (11d, 41d) concavely provided at the other of the heat radiation member (11, 41) and the insulation member (13, 43) and configured to be fitted with the position determining pin (21c, 51c); a biasing member (14, 44) suitable for holding the heat radiation member (11, 41) and the insulation member (13, 43) along with the electronic component by elastically contacting a first end (22, 52) and a second end (23, 53) thereof with the engaging groove (11a, 41a) and the insulation member (13, 43), respectively and by contacting a portion of said biasing member (14, 44) situated between said first end and said second end with the lateral contacting surface (11c, 41c) of the heat radiation member (11, 41); wherein the central attaching surface (11b, 41b) of the heat radiation member (11, 41) is configured to be attached with an external heat radiation member; and wherein the biasing member (14, 44) includes a biasing portion (24, 55) which projects above the central attaching surface (11b, 41b) when the electronic component is fixed in its final position by said biasing member (14, 44), said biasing portion being configured to elastically contact said external heat radiation member.