A solid-state imaging element including: a sensor substrate in which a photoelectric conversion section is arranged and formed; a circuit substrate in which a circuit for driving the photoelectric conversion section is formed, the circuit substrate being laminated to the sensor substrate; a sensor side electrode drawn out to a surface of the sensor substrate on a side of the circuit substrate and formed as one of a projection electrode and a depression electrode; and a circuit side electrode drawn out to a surface of the circuit substrate on a side of the sensor substrate, formed as one of the depression electrode and the projection electrode, and joined to the sensor side electrode in a state of the circuit side electrode and the sensor side electrode being fitted together.