The present invention relates to a washing agents dispenser device, in particular for dishwashing machines, comprising: - a body(2’,52), - at least a compartment(4’,53,53’) in said body(2’,52) for containing a washing agent, - a cover(5’,54) associated to said compartment (41,53,531), being movable at least from a closed position to an open position of said compartment(4’,53,53’), - means(16’,17’A,17’B,54A,60) for restraining said cover(5’,54) to the body(2’,52), so that said cover(5’,54) is capable of moving according to a substantially plane motion at least for a length of its movement between said open and closed positions, - a locking/release system(8’,9’,10’, 11’,12’,13’,8’’,8A,9’’,10 ' ,1111) of said cover(5’,54) comprising actuating means, - first sealing means(4’E,4’I and 4’ß,57) associated to said compartment(4’,53,53’), - second sealing means(15’,55,55’Y) associated to said compartment(5’,54), where in their mutual cooperation, said first sealing means(4’E, 411 and 4’ß,57) and said second sealing means (15',55,55') identify and delimit a sealing surface being apt to ensure at least a partial sealing of the compartment(4’,53,53’) when said cover(5’,54) is in its closed position.