Pumas scored seven tries in biggest winning margin and points tally against the Welsh.
Wales scored four tries with scrum-half Tomos Williams and hooker Dewi Lake going over in the first half and flanker Jac Morgan and full-back Blair Murray after the break.
Wales take on Japan in their second autumn Test on Saturday.
Live Reporting
Matt Lloyd
Jarrod Evans' impactpublished at 74 mins
74 mins
Wales 28-45 Argentina
Scott Williams Wales centre on BBC Radio Cymru
The game has opened up and it suits the way that Jarrod Evans plays. The tempo has increased since he's come on.
When Wales have got into Argentina's 22, they have scored tries with some ease but it's what happens in the middle of the pitch that is proving to be the problem.
Converted try: Wales 28-45 Argentinapublished at 73 mins
73 mins
Murray try, Evans con
The wing sails through for his third Test try.
Wales at least fighting to the end.
Murray's initial break got Wales upfield. From the resulting scrum, Ben Thomas and then Archie Griffin go close before Tomos Williams fizzes a flat pass across three players to hand Murray an easy finish.
We're just seeing Jac Morgan being comforted - or rather consoled - by teammates as he returns to his seat among the replacements with his arm in a sling.
Converted try: Wales 21-45 Argentinapublished at 62 mins
62 mins
Prisciantelli try, S Carreras con
Interception and Argentina have a sixth.
Just as Wales were growing with confidence, Ben Thomas tried to find Tomos Williams on the loop pass - just as he did to great effect with Dan Edwards moments ago.
But this time Argentina saw it coming and the fly-half read the play to perfection, snatching the ball and racing clear from 25 metres out for his second of the day.
Fabulous break by Dan Edwards brings the stadium to its feet.
He looped around the back of the Welsh line, racing onto Ben Thomas' clever pass and weaved his way up field before he's felled by an ankle-tap just when he thought he was clear.
Oh the ankle tap... one of the best sights in rugby.
He was already warming up to come on for someone but Morgan's injury means he takes over from the captain for his Test debut at the age of 31. That's a long time to wait!