An image sensor module (X1) includes a housing (1), a lens retainer (2), an image sensor chip (4), a substrate (5) and a lens unit (A, B). The housing (1) is formed with a step portion (1a) for fixing the lens unit (A, B). The lens retainer (2) is fixed to the housing (1) and held in contact with the upper face of the lens unit (A, B). The lens unit (A, B) is pressed against the step portion (1a) of the housing (1) by a biasing force of the lens retainer (2).