An oil-immersed solenoid used for hydraulic control equipment, the oil-immersed solenoid comprising: a casing including a base, a cylindrical cylinder extending from the base, and a flange extending from the base to an outside of the cylinder (12, the base, the cylinder and the flange being integrally formed; a fixed magnetic pole disposed to extend from the base into the cylinder; a plunger including a shaft inserted into an insertion hole extending along an axis of the fixed magnetic pole, and an armature to which the shaft is fixed; a cylindrical guide pipe fitted to an outer circumference of the fixed magnetic pole to cover the plunger; a coil unit including a main body around which a coil is wound, and a connector provided on an outer circumferential face of the main body; and a cover disposed in the cylinder to cover the guide pipe and the coil unit from an opposite side to the base of the casing, wherein the fixed magnetic pole is integrated with the casing or the fixed magnetic pole is attached to the casing, the cylinder of the casing has a notch cut in a circumferential direction to correspond to the connector of the coil unit, the plunger is attached in the cylinder of the casing so as to insert the shaft into the insertion hole of the fixed magnetic pole, the guide pipe is fitted to the outer circumference of the fixed magnetic pole to cover the plunger, the coil unit is inserted into a gap between the cylinder of the casing and the guide pipe, the cover is attached to cover the guide pipe and the coil unit, and in this state, a front end of the cylinder is swaged to the cover, to hold the plunger, the guide pipe, the coil unit, and the cover in the casing, and a yoke is integrated with the coil unit, the yoke disposed adjacent to the main body on a side where the cover is arranged, and having an outer circumference of a larger outer diameter than the coil unit, and a step engaged with the outer circumference of the yoke is formed on an inner face of the cylinder of the casing, and the cover is swaged to the yoke. a casing including a base, a cylindrical cylinder extending from the base, and a flange extending from the base to an outside of the cylinder (12, the base, the cylinder and the flange being integrally formed; a fixed magnetic pole disposed to extend from the base into the cylinder; a plunger including a shaft inserted into an insertion hole extending along an axis of the fixed magnetic pole, and an armature to which the shaft is fixed; a cylindrical guide pipe fitted to an outer circumference of the fixed magnetic pole to cover the plunger; a coil unit including a main body around which a coil is wound, and a connector provided on an outer circumferential face of the main body; and a cover disposed in the cylinder to cover the guide pipe and the coil unit from an opposite side to the base of the casing, wherein the fixed magnetic pole is integrated with the casing or the fixed magnetic pole is attached to the casing, the cylinder of the casing has a notch cut in a circumferential direction to correspond to the connector of the coil unit, the plunger is attached in the cylinder of the casing so as to insert the shaft into the insertion hole of the fixed magnetic pole, the guide pipe is fitted to the outer circumference of the fixed magnetic pole to cover the plunger, the coil unit is inserted into a gap between the cylinder of the casing and the guide pipe, the cover is attached to cover the guide pipe and the coil unit, and in this state, a front end of the cylinder is swaged to the cover, to hold the plunger, the guide pipe, the coil unit, and the cover in the casing, and a yoke is integrated with the coil unit, the yoke disposed adjacent to the main body on a side where the cover is arranged, and having an outer circumference of a larger outer diameter than the coil unit, and a step engaged with the outer circumference of the yoke is formed on an inner face of the cylinder of the casing, and the cover is swaged to the yoke.