An endoscope comprising: an imaging unit disposed at a distal end portion of an insertion section inserted into a body of a subject; and a built-in component provided parallel with the imaging unit at the distal end portion, and extending substantially parallel with an axial direction of the insertion section, wherein the imaging unit includes: a solid state image sensor including a light receiving unit; a flexible circuit board electrically connecting the solid state image sensor; and a rigid circuit board at least partially disposed on a proximal end side of the endoscope relative to the solid state image sensor, and electrically connected to the flexible circuit board, the rigid circuit board includes a first surface whose longitudinal direction extends in an axial direction of the distal end portion, and a second surface opposed to the first surface substantially in parallel, the first surface having a width larger than a width of the second surface in a cross-section orthogonal to the longitudinal direction, the rigid circuit board includes a third surface and a fourth surface, different from the first surface and the second surface, the third surface and the fourth surface extending in an axial direction of the distal end portion, and the third surface or the fourth surface being opposed to the built-in component, the solid state image sensor includes a light receiving surface provided with the light receiving unit, a land on the sensor for connection with the flexible circuit board is formed on the light receiving surface, and the light receiving surface is disposed orthogonal to the axial direction of the distal end portion, the rigid circuit board is formed with a land on the circuit board for connection with the flexible circuit board, on the first or second surface (S1, S2), and is disposed such that a fifth surface orthogonal to the axial direction of the distal end portion is opposed to a surface opposite to the light receiving surface of the solid state image sensor, and the flexible circuit board is disposed to be opposed to a side surface of the light receiving surface of the solid state image sensor, and the first or second surface (S1, S2) of the rigid circuit board. an imaging unit disposed at a distal end portion of an insertion section inserted into a body of a subject; and a built-in component provided parallel with the imaging unit at the distal end portion, and extending substantially parallel with an axial direction of the insertion section, wherein the imaging unit includes: a solid state image sensor including a light receiving unit; a flexible circuit board electrically connecting the solid state image sensor; and a rigid circuit board at least partially disposed on a proximal end side of the endoscope relative to the solid state image sensor, and electrically connected to the flexible circuit board, a solid state image sensor including a light receiving unit; a flexible circuit board electrically connecting the solid state image sensor; and a rigid circuit board at least partially disposed on a proximal end side of the endoscope relative to the solid state image sensor, and electrically connected to the flexible circuit board, the rigid circuit board includes a first surface whose longitudinal direction extends in an axial direction of the distal end portion, and a second surface opposed to the first surface substantially in parallel, the first surface having a width larger than a width of the second surface in a cross-section orthogonal to the longitudinal direction, the rigid circuit board includes a third surface and a fourth surface, different from the first surface and the second surface, the third surface and the fourth surface extending in an axial direction of the distal end portion, and the third surface or the fourth surface being opposed to the built-in component, the solid state image sensor includes a light receiving surface provided with the light receiving unit, a land on the sensor for connection with the flexible circuit board is formed on the light receiving surface, and the light receiving surface is disposed orthogonal to the axial direction of the distal end portion, the rigid circuit board is formed with a land on the circuit board for connection with the flexible circuit board, on the first or second surface (S1, S2), and is disposed such that a fifth surface orthogonal to the axial direction of the distal end portion is opposed to a surface opposite to the light receiving surface of the solid state image sensor, and the flexible circuit board is disposed to be opposed to a side surface of the light receiving surface of the solid state image sensor, and the first or second surface (S1, S2) of the rigid circuit board.