The present invention relates to a washing agents dispenser device, in particular for dishwashing machines, comprising: a a body 2' 52, b at least a compartment 4' 53 53' in said body 2' 52 for containing a washing agent, c a cover 5' 54 associated to said compartment 4' 53 53', being movable at least from a closed position to an open position of said compartment 4' 53 53', d means 16', 17'A, 17'8 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, e a locking/release system 8', 9', 10', 11', 12', 13' 8", 8A, 9", 1 0", 11 " of said cover 5' 54 comprising actuating means, f first sealing means 4'E, 4'1 e 4'8 57 associated to said compartment 4', 53 53', g second sealing means 15' 55 55' associated to said compartment 5' 54, where in their mutual cooperation, said first sealing means 4'E, 4'1 and 4'8 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. A feature of the present invention is represented by the sealing surface at least partially inclined with respect to the plane identifying said substantially plane motion of the cover 5', mainly in view of facilitating the closing operation of the cover 5' by the user of the dishwashing machine incorporating the dispenser device.