Dispensing device of washing agents for a household washing machine, in particular a dishwasher, said dispenser (1) having at least a tank (S) for a liquid washing agent and an arrangement for dispensing a dose of said liquid washing agent, wherein this arrangement comprises: a passage (15A,15,17A,17), being apt to put the inside of the tank (S) in hydraulic communication with a discharge outlet (21) for said liquid washing agent; first plugging means (18), act on said passage (15A,15,17A,17) and capable of taking a first position due to which the washing agent cannot reach said discharge outlet (21), and a second position due to which the washing agent is able to reach said discharge outlet; actuating means (13) producing actuation of said first plugging means (18). According to the invention, controllable safety means (16) act along said passage (15A,15,17A,17) are provided, which normally operate for preventing washing agent downflow from said tank (S) to said passage (15A,15,17A,17), independently from the position or state of the first plugging means (18).