A motor device comprising: a motor ; a first substrate on which a first element group is provided; a second substrate on which a second element group is provided, the second element group having a heat generation amount larger than a heat generation amount of the first element group , the second substrate being placed to face the first substrate in a plate-thickness direction of the second substrate ; a first heat sink placed between the first substrate and the second substrate , the first heat sink being configured to promote heat dissipation from the first element group and the second element group ; a second heat sink placed on an opposite side of the second substrate from the first heat sink , the second heat sink being configured to promote heat dissipation from the second element group , and a motor housing in which the motor is accommodated, the motor housing being bottomed tubular, wherein the first heat sink is fixed to the motor housing , the first heat sink is configured to make thermal contact with the motor housing via a fixed part of the first heat sink to the motor housing , the first heat sink includes a body portion facing the first substrate and the second substrate , the first heat sink includes a housing portion connected to the body portion, the housing portion being configured to surround a periphery of the body portion and exposed to outside the motor device , the second heat sink closes the opening of the motor housing and is fixed to an inner wall surface of the motor housing , and the second heat sink is configured to make thermal contact with the motor housing via a fixed part of the second heat sink to the motor housing . a motor ; a first substrate on which a first element group is provided; a second substrate on which a second element group is provided, the second element group having a heat generation amount larger than a heat generation amount of the first element group , the second substrate being placed to face the first substrate in a plate-thickness direction of the second substrate ; a first heat sink placed between the first substrate and the second substrate , the first heat sink being configured to promote heat dissipation from the first element group and the second element group ; a second heat sink placed on an opposite side of the second substrate from the first heat sink , the second heat sink being configured to promote heat dissipation from the second element group , and a motor housing in which the motor is accommodated, the motor housing being bottomed tubular, wherein the first heat sink is fixed to the motor housing , the first heat sink is configured to make thermal contact with the motor housing via a fixed part of the first heat sink to the motor housing , the first heat sink includes a body portion facing the first substrate and the second substrate , the first heat sink includes a housing portion connected to the body portion, the housing portion being configured to surround a periphery of the body portion and exposed to outside the motor device , the second heat sink closes the opening of the motor housing and is fixed to an inner wall surface of the motor housing , and the second heat sink is configured to make thermal contact with the motor housing via a fixed part of the second heat sink to the motor housing . <EOS>